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Hi guys,

My starlet was being mapped today and my tuner ran into some issues maxing out my injectors.

Im looking to replace the injectors but looking for peoples opinion on what injectors to go for please. Im wanting to push for 300hp so was thinking 1000cc injectors would be sensible.

I currently have rx7 550cc injectors which though they would be sufficient but obviously not.

it made 215hp at 1.3 bar boost. upped to to 1.5 bar and made 240ish hp but maxed out injectors at this level.

 

Brief spec of the car is;

4efte with forged rods and pistons - new bearings seals etc but unknown piston size whether its standard or oversized. believe likely to be standard size

rebuilt and very lightly ported head

WEPR gtx28 turbo kit with 0.52 tial exhaust housing, tial ext wastegate etc

3" exhaust 

standard inlet

 

Could people recommend any injectors they would suggest? price and quality etc etc

i think the power level seems low comparing to others at similair boost pressures so interested in other peoples thoughts.

thanks

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You should not be maxing a 550cc at 240bhp so you may have other hardware issues on the car so you should investigate the complete fuel system. 
 

For a cost effective option I usually recommend the Bosch CP ones. From the time I’ve spent on the dyno with the 630’scc they usually will do around 350bhp fly on a 4E with GT28 but that’s pretty close to flat out on them at stock fuel pressure. 
 

You can get larger if required, for bigger turbo / higher power setups you can use the Bosch CP 1000s,  but for best control on 95% of 350+ bhp car I recommend Injector Dynamics 1050x. For reference a 1000cc you can make upwards of 450bhp fly on a 4E (tried and tested and still not maxed out) 

Who was mapping the car? Did they look into any of the fuel system components to help you fault find?

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13 hours ago, RobSR said:

You should not be maxing a 550cc at 240bhp so you may have other hardware issues on the car so you should investigate the complete fuel system. 
 

For a cost effective option I usually recommend the Bosch CP ones. From the time I’ve spent on the dyno with the 630’scc they usually will do around 350bhp fly on a 4E with GT28 but that’s pretty close to flat out on them at stock fuel pressure. 
 

You can get larger if required, for bigger turbo / higher power setups you can use the Bosch CP 1000s,  but for best control on 95% of 350+ bhp car I recommend Injector Dynamics 1050x. For reference a 1000cc you can make upwards of 450bhp fly on a 4E (tried and tested and still not maxed out) 

Who was mapping the car? Did they look into any of the fuel system components to help you fault find?

Thanks rob your reply is very helpful.

I’ve referred this back to my tuner and they are investigating. 
they are saying it’s holding 4 bar fuel pressure and it’s stable so unsure really.

the only fuel lines I’ve had changed is from the standard hard lines to the adjustable regulator to the fuel rail and then back to the hard line. From what the tuner has said this is 6mm like and should be adequate for what we need in this application?

I would take your advice with the injectors Thankyou but just a little concerned about maxing the current ones at this level. I don’t really know what could be causing the issue then.

it’s with a company called m-tech automotive in west bury. They are partnered with motorsport electronics which have made and supplied the me442 stand-alone ecu I have fitted and is being tuned by them. They specialise more in mx5 turbos but thought it a good idea to have it tuned by the people that make the plug and play ecu for the starlet..

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Matt at motorsport electronics who is tuning has clarified we are making about 245hp at 1.3/1.35 bar boost.

Having spoken now with ricky at racetech as he has experience with high power starlets (my tuner suggested a quick call with him for his input), hes also advising that we are about 100hp down on power at this boost pressure so does seem to be an underlying issue somewhere here.

They are going to do a leak down and smoke test to see where there may be a problem..

I had a greddy tdo05 14b turbo kit on the car before and this only made 190hp when tuned by them before covid. didnt drive the car through covid and then upgraded the turbo kit as it was an unkown turbo kit and i wanted more power so maybe there is an underlying issue here. Any thoughts on what it could be?

 

@RobSR - are these the injectors your talking about?

https://www.tuningdevelopments.uk/product_info.php?cPath=502_520_590&products_id=827

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Take the RT comment with a pinch of salt, you won’t make 345 @ 1.4 bar unless you have a very well built head. 
 

A 2860 usually makes around 350 with completely stock head (unported etc) nearer to 1.8 bar

It sounds like the power may be a little low, however this could be caused by a lot of variables, including the ignition advance the mapper has decided to use also. 
 

For the fuel system, you need to check the various components, and get the injectors cleaned/flow tested too. 
 

Stock fuel lines with a FPR are fine again for 350+ bhp. 
 

Yes they are the injectors but the older version by the sounds, I can supply the newer 1050X variant if needed, but in most instances the Bosch CP ones will be fine .

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I also messaged Sacha at WEPR who i bought the kit from and he definately thought it was down on power. Mattwho is tunning it does say his rolling road dyno reads less than other but i dont know.

the head i have is mildly port and polished nothing crazy but standard cams, springs etc. 

From what ive read over the years 300-330hp is achievable on standard head and inlet.. that's what i was working on really and wasnt planning at this stage going for a fully built head.

I had considered coil on plug conversion to improve the ignition side of things but have believed that people have run 300hp on th standard dizzy setup.

My car is a uk n/a and not a glanza but i dont believe the hard fuel lines differ to be honest.

Im just conscious of pushing the car and raising boost levels if there is an underlying problem. I have asked they do a smoke and leakdown test on the engine next week so start from there really.

Could you pm me what you would supply them for? i had a quick look on you website and you did do plug and pluy convertors? id be interested if you could.

Thanks for your help so far. been very helpful.

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On 2/18/2022 at 7:40 PM, snails ep91 said:

I also messaged Sacha at WEPR who i bought the kit from and he definately thought it was down on power. Mattwho is tunning it does say his rolling road dyno reads less than other but i dont know.

the head i have is mildly port and polished nothing crazy but standard cams, springs etc. 

From what ive read over the years 300-330hp is achievable on standard head and inlet.. that's what i was working on really and wasnt planning at this stage going for a fully built head.

I had considered coil on plug conversion to improve the ignition side of things but have believed that people have run 300hp on th standard dizzy setup.

My car is a uk n/a and not a glanza but i dont believe the hard fuel lines differ to be honest.

Im just conscious of pushing the car and raising boost levels if there is an underlying problem. I have asked they do a smoke and leakdown test on the engine next week so start from there really.

Could you pm me what you would supply them for? i had a quick look on you website and you did do plug and pluy convertors? id be interested if you could.

Thanks for your help so far. been very helpful.

Yes usually upto 330-350 ish at 1.7 bar on your turbo id expect 

Yes stock dizzy is fine at 300-350 too, when you start running higher boost levels the stock coil can struggle to give you the spark energy you need. 
 

N/A fuel lines also ok. 
 

Ask the guy mapping it what AFR and final injector pulse width you’re seeing at 1.4 bar around 6000 rpm. 
 

will PM you too.

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On 2/19/2022 at 8:32 PM, Sam44 said:

Just seen this now snails. 

The starlet is the first time I've used denso injectors of this period. They are frustrating. 

Keep us updated. Very surprising result on that turbo. 

Hi mate, yes will keep you updated. 

this car has fought me every step of the way to be honest so im not even surprised with the issues im having now.

just dont want to run the car if there is underlying issues causing it to be so relatively underpowered.

your comments on the denso injectors. can you elaborate?

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23 hours ago, RobSR said:

Yes usually upto 330-350 ish at 1.7 bar on your turbo id expect 

Yes stock dizzy is fine at 300-350 too, when you start running higher boost levels the stock coil can struggle to give you the spark energy you need. 
 

N/A fuel lines also ok. 
 

Ask the guy mapping it what AFR and final injector pulse width you’re seeing at 1.4 bar around 6000 rpm. 
 

will PM you too.

I was assuming similair figures, approx 300-330 with my setup, mildly ported head but standard inlet cams springs etc.

good news on dizzy as wont change right now if not needed as added expenditure.

ive never seen/heard of n/a fuel lines being different but just tryng to rule any potential issues here. thanks for your input.

The mapper said the AFR's were where they needed to be and were good he mentioned over the phone 11-11.4 something like that. dont have info on injectors but can ask.

got your pm and will respond now

cheers

 

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No worries, the physical injector opening time will tell the tale, but it sounds like with the DC you’re running at said boost you’d be very rich which would then also effect power.

You say they checked the fuel pressure, which 9 times out of 10 is the issue on starlets on the dyno, I’ve had it easily on 5 cars when tuning them, you’ll keep adding fuel, injector PW goes up, but the lambda doesn’t read any richer as the fuel pump can’t keep up. It’s common and then you end up with a funny looking fuel table too. 
 

If they are certain the fuel pressure is fine and isn’t dropping on boost, it may be clogged injectors, or they may be calibrating against a Lambda which is reading massively wrong. 
 

Did you ever have your injectors tested? 

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These engines have a poor cyl mixing. I can only put it down to the very narrow squish zones, narrow opposed cam angle (eco head) leading to a wedge shape combustion chamber, and thick head gasket, couple this wwith batch firing and the denso injectors having caps were the spray outlet is.

Like said it was only when I started work on the fuel system things really started to get alot better, mainly upping fuel pressure atomised the fuel better. I noticed a big improvement in exhaust gases and exhaust temps. 

saying this I have been told that the last of the 98 spec v uses the 4efe inlet cam. And can struggle for big power. I think Toyota were starting to stop production on many items. Things also like cam to follow clearance checked. 

Im running mine in open loop also. As soon as it goes into closed loop the lamba sends the fueling vey rich messing things right up. 

Ive had a gt were the coil kv was low affecting topend power. 

These cars have a very very basic/poor earthing to chassis return, with the fuel pump, engine sensors ignition amp/ignitor, spark plugs and fuel pump using it. A good direct earth return to battery works wonders. 

Also the amount of these I've seen now were everything, boost gauge, boost controller, bov valve are all plumed into the map sensor signal/pressure pipe. The map sensor now has to deal with pressure waves and a delayed signal because of the extra added volume these pipes bring. Make sure your map sensors have there own pipe to the manifold and it's only as long as it needs to be.

Edited by Sam44
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On 2/21/2022 at 3:47 PM, RobSR said:

No worries, the physical injector opening time will tell the tale, but it sounds like with the DC you’re running at said boost you’d be very rich which would then also effect power.

You say they checked the fuel pressure, which 9 times out of 10 is the issue on starlets on the dyno, I’ve had it easily on 5 cars when tuning them, you’ll keep adding fuel, injector PW goes up, but the lambda doesn’t read any richer as the fuel pump can’t keep up. It’s common and then you end up with a funny looking fuel table too. 
 

If they are certain the fuel pressure is fine and isn’t dropping on boost, it may be clogged injectors, or they may be calibrating against a Lambda which is reading massively wrong. 
 

Did you ever have your injectors tested? 

Im going to discuss this with the mapper.

i was told it was holding 4 bar fuel pressure consistently. 

I did have them cleaned and tested but that was in the build process and was some years ago. unfortunately i dont have any information more than that as was done with other works. 

I have a brand new AEM Lambda gauge and sensor with only 5/600 miles on it in the car. dont they also put their own lambda sensor in the car exhaust when tuning? this would be obvious no? 

 

On 2/22/2022 at 2:33 PM, gorganl2000 said:

what fuel pump size are you running at the moment? and how old is it?

its a walbro pump (i really cant remember which one but is uprated) but is quite old now tbh. probably 7 years old (hangs head in shame with how long build process has taken) but probably hasnt done more than 3000 miles in its life. im being told its holding fuel pressure fine though..

 

On 2/23/2022 at 8:08 AM, Sam44 said:

These engines have a poor cyl mixing. I can only put it down to the very narrow squish zones, narrow opposed cam angle (eco head) leading to a wedge shape combustion chamber, and thick head gasket, couple this wwith batch firing and the denso injectors having caps were the spray outlet is.

Like said it was only when I started work on the fuel system things really started to get alot better, mainly upping fuel pressure atomised the fuel better. I noticed a big improvement in exhaust gases and exhaust temps. 

saying this I have been told that the last of the 98 spec v uses the 4efe inlet cam. And can struggle for big power. I think Toyota were starting to stop production on many items. Things also like cam to follow clearance checked. 

Im running mine in open loop also. As soon as it goes into closed loop the lamba sends the fueling vey rich messing things right up. 

Ive had a gt were the coil kv was low affecting topend power. 

These cars have a very very basic/poor earthing to chassis return, with the fuel pump, engine sensors ignition amp/ignitor, spark plugs and fuel pump using it. A good direct earth return to battery works wonders. 

Also the amount of these I've seen now were everything, boost gauge, boost controller, bov valve are all plumed into the map sensor signal/pressure pipe. The map sensor now has to deal with pressure waves and a delayed signal because of the extra added volume these pipes bring. Make sure your map sensors have there own pipe to the manifold and it's only as long as it needs to be.

Thats interesting i will check the boost hose routes as we had a faulty map sensor when we got the car running. this was replaced and resolved but worth looking at.

the wiring loom is a standard glanza loom on this. i did used to have a grounding kit on my n/a maybe ill look into this. not something ive seen on many starlets though.

 

Im considering replacing the fuel injector and pump as they are now old. im being told the injectors are maxing out but fuel pressure is consistent so would this be the case if fuel pump wasn't adequate.

so just still a bit confused as to what to do now tbh. The garage have done a leak down/smoke test and has all come back good with no leaks and compression tested and is good. just a bit stumped as to whats the best step to take with it now. 

i dont want to tell them to keep throwing boost at it to try and get power as it should be making more from what im told at the boost level its at. 

If there was an earthing issue wouldny this be detedtable under power?

im really at a loss to what the issue could be. 

When i had it running on its previous setup greddy td05 14b, it was bought of a guy who had about 260hp out of it  on a forged 1.3 (so i was told) and i only made 190hp at 1 bar of which raising the boost pressure was just generating too much heat and not achieving more power so i was told by the mapper. so i dont know if this is linked with being down on power now as well.

 

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You’d see the earth issue via the voltage in the ecu as injectors are on the same circuit 

If fuel pressure is fine, it may just be an injector issue - it’s possible they may not actually be 550’s? 
 

yes they should fit their own dyno lambda too so they can compare between the AEM reading; the AEM are notoriously unreliable however, I’ve seen them read a whole 1.0:1 either way than what my calibrated dyno lambda read.

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As many electricians know resistance on a corroided earth contact will affect current/amp. Not voltage.  it will only effect voltage as the contact is about to die, it's the spark duration it hits first. As a reference "the bulb is dim but the voltage is fine", a common electrical fault. 

The fuel pump also uses a chassis earth. 

Have you checked your cam timing. Especially the inlet to exhaust gear cam timing, and cam to valve clearance gaps. Also what spark plugs are you using. 

Edited by Sam44
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On 2/25/2022 at 7:54 PM, RobSR said:

You’d see the earth issue via the voltage in the ecu as injectors are on the same circuit 

If fuel pressure is fine, it may just be an injector issue - it’s possible they may not actually be 550’s? 
 

yes they should fit their own dyno lambda too so they can compare between the AEM reading; the AEM are notoriously unreliable however, I’ve seen them read a whole 1.0:1 either way than what my calibrated dyno lambda read.

Im being told its holding 4 bar fuel pressure no problem, so im hoping it is an injector issue.

im certain they are rx7 550cc injectors. but its been so long since i bought them i cant say 100%. im going to replace them to be sure. will send you a pm regarding those inectors mate.

yes i believe they will have used their own lambda sensor but ill ask the question tomorrow.

On 2/26/2022 at 1:30 PM, Sam44 said:

As many electricians know resistance on a corroided earth contact will affect current/amp. Not voltage.  it will only effect voltage as the contact is about to die, it's the spark duration it hits first. As a reference "the bulb is dim but the voltage is fine", a common electrical fault. 

The fuel pump also uses a chassis earth. 

Have you checked your cam timing. Especially the inlet to exhaust gear cam timing, and cam to valve clearance gaps. Also what spark plugs are you using. 

I have relocated the battery to the boot and have a large cable earthed to the chassis. its bolted to the area where the spare wheel would sit as that is where the battery sits. i dont know if this needs improving.

i will ask them to look at the cam timing

they recently replaced the spark plugs but i dont know what with. again ill find out.

thanks for your help guys its much appreciated.

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car was taken to get alignment done and there was a starting issue when left there. they got the vehicle back to the garage and investigated that there was an earthing issue. 

they have upgraded the chassis to engine earthing and it is firing up no issue now. they said they would have expected a misfire if this was causing a major issue when dynoing the car before but still, an issue has been found.

we are going to run it on the dyno this week now there has been an issue identified and hopefully this could have been the problem we are looking for..

 

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As soon as I saw the surging of the headlights as the engine revs up and dims again as it returned to idle I know the electrical system on these was poor at very best. Then I started to investigate, and found its very poor.

A larger capacity battery helps a great deal. 

Rember to run a earth to the engine sensor earth bank. And the ignitor/ignition amp also benefits from a solid return earth. This attaches to the frame/mounting bracket. The ignitor earth is internal to the alloy cover. 

Littraly every system on this little car is so very basic. 

Edited by Sam44
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1 hour ago, Sam44 said:

As soon as I saw the surging of the headlights as the engine revs up and dims again as it returned to idle I know the electrical system on these was poor at very best. Then I started to investigate, and found its very poor.

A larger capacity battery helps a great deal. 

Rember to run a earth to the engine sensor earth bank. And the ignitor/ignition amp also benefits from a solid return earth. This attaches to the frame/mounting bracket. The ignitor earth is internal to the alloy cover. 

Littraly every system on this little car is so very basic. 

I had a new battery installed last year which should be capable from its size. 

when i gt the car back im going to look into earthing some additional parts to improve upon this. thanks for the tips. 

the car is going back on the dyno this week to see what impact the new thicker earthing has if any and then im purchasing some 1050cc injectors to see where we go from there.

more money! We'll see what comes of it this week and ill report back.

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  • 2 weeks later...

So ive had a message to say the car has been back on the dyno since the block to chassis earthing issue was identified.

They have apparently leaned the car out and have now made 270hp  but they do not like the fueling at this level and want to richen it back up and change injectors.

I have ordered 1050cc injector dynamics injectors which should be here in the next week or so so will have the car remapped with these and hope it performs better. 

Im hoping its the current injectors that could be limiting the power but we will wait and see what happens.

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5 hours ago, Sam44 said:

Keep us updated, love the trials tunning/modding brings. 

The injectors are definitely a great step. The denso units are hard work. 

my bank account doesnt lol. I wish i understood it more to take on a more hands on approach but this is all a learning curve isnt it.

Im hoping replacing the likely now 30 year old rx7 injectors with modern larger units will be a big improvement.

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