KPJUK Posted June 23, 2015 Share Posted June 23, 2015 Hi guys, After having much fun hooning time I am getting sick of an intermittent misfire (which is now getting worse and more regular) which is most noticeable pulling from low RPM in a high gear. It really sputters and craps out and backfires every now and then. I have a CEL and after checking the code I have only got Code 42 - Vehicle Speed Sensor. What sensor is this referring to exactly and could it have some effect on the engine management? It seemed to be fine all day today but after going out tonight it is as if the car is stopping the hooliganism. Sad times. If I accelerate smoothly I don't seem to have a misfire. If I plant the throttle it can hesitate sometimes. When revving in neutral from idle it can be very grumbly. Any ideas here? It will get me home for sure but I want to minimise damage to the engine if this is harming it in any way. KP Quote Link to post Share on other sites
daniel_g Posted June 24, 2015 Share Posted June 24, 2015 Check the dizzy cap and rotor arm for cracks, damage, signs of moisture.Also worthwile carring out a resistance check on the leads. Quote Link to post Share on other sites
5e colin Posted June 24, 2015 Share Posted June 24, 2015 if al that fails it might be a leaky valve leakdown could give some signs Quote Link to post Share on other sites
KPJUK Posted June 24, 2015 Author Share Posted June 24, 2015 There's no dizzy cap its a twin coil wasted spark ignition system But thank you - we did test the leads just today! We tested the HT leads and coils for resistance and they are absolutely spot on. The Spark Plugs could do with replacing but wouldn't cause this issue. What we did find using a Gunson Colour Tester is that the engine is running lean under full throttle = fuel supply issue. When we applied a positive pressure to the pressure regulator it appeared to ease the misfire, thus I will be fitting an adjustable fuel pressure regulator to bring the pressure up to snuff. That should have it sorted. Does anyone know of a decent kit for not much money that bolts straight on? I want to raise it to 2.8Bar if possible. KP Quote Link to post Share on other sites
daniel_g Posted June 24, 2015 Share Posted June 24, 2015 Forgot you were using the Gen3 DIS ignition system.As for the FPR, dont get the cheapest one you can find (ebay) because they are dog shit, stick at 4bar and cause hassle.Something like an aeromotive, sard, etc and you'll be sorted. Quote Link to post Share on other sites
KPJUK Posted June 24, 2015 Author Share Posted June 24, 2015 Ah ok thanks for the advice, I was looking at this one but may rethink that: http://www.ebay.co.uk/itm/UNIVERSAL-FUEL-PRESSURE-REGULATOR-TOYOTA-MR2-CELICA-SUPRA-STARLET-W-GAUGE-RED-/271300630796?pt=LH_DefaultDomain_3&hash=item3f2ac7190c The misfire is getting bad - anyone got a spare lambda sensor? I only have the one heated sensor and its Bosch not the genuine Denso so I think its giving duff readings. ECU hasn't whinged about it but it may be part of the issue. KP Quote Link to post Share on other sites
daniel_g Posted June 24, 2015 Share Posted June 24, 2015 Stay well clear of those FPRs dude.Is it the 4 wire o2 sensor on that engine then being the Gen3? Quote Link to post Share on other sites
KPJUK Posted June 24, 2015 Author Share Posted June 24, 2015 Ok thanks mate will do. Yeah its the 4 wire heated sensor. I have a Bosch unit on there now but no clue if its sending the right signals. ] KP Quote Link to post Share on other sites
KPJUK Posted June 24, 2015 Author Share Posted June 24, 2015 This one looks about right - according to the Denso catalogue the direct fit to the original downpipe is the DOX-0225 (1997-1999) and the universal sensor is DOX-0111 which is £35 not £80! I need the universal one anyway, can someone take a look at this and confirm I'm not talking bollox? http://www.autodesignplus.because/editor/image/stranky3_soubory/d-denso-lambda-sensor-catalogue-2008-2009.pdf KP Quote Link to post Share on other sites
KPJUK Posted June 25, 2015 Author Share Posted June 25, 2015 Having reconnected the O2 sensor and checked its voltage, I can confirm that it is working between 0.1v and 0.9v which is as specified by Denso and Bosch - so I believe I am safe in assuming they both send the same signal and it shouldn't make a difference to the ECU which one I use. Annoyingly it didn't solve anything however I may try resetting the ECU tomorrow with it connected and see if it responds better. KP Quote Link to post Share on other sites
KPJUK Posted June 25, 2015 Author Share Posted June 25, 2015 Sure enough, I couldn't see the wood through the trees. After installing a new set of Spark Plugs and chucking some fuel system cleaner in the tank the misfire has disappeared. Runs spot on now! KP Quote Link to post Share on other sites
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