Mike2JZ Posted January 18, 2015 Share Posted January 18, 2015 So a while ago, I had a heater hose split behind the engine, which caused coolant to piss everywhere, including the spark wells. After cleaning the spark wells and placing new sparks the supra developed a misfire at idle My theory is that whilst the coolant pissed out, the rising temperature must have caused some damage (even though the car was stopped asap once I noticed temps rising) I left the car to sit idle for a month whilst I was away, upon my return nothing has changed. So the current symptoms are: No misfire when cold, but develops once warm. Misfire most noticeable at idle which sounds like: Lost power across rev range Engine bogs down whilst accelerating Occasional strong vibrations whilst engine sits at low rpm's Idle with cold starts @ 1800-2000rpm, before dropping to 1000-1100 Idle with warm start @ 900-1000rpm Currently I have done the following to try and alleviate the issue (with no luck): Checked engine error codes - No codes to display Reset ECU - No noticeable change Cleaned out spark plug wells Installed new spark plugs Whilst car was idling, I tested the HT leads for each spark by removing and listening for the idle to change. All cylinders showed a negative change in idle once their respective HT lead was removed. So makes me think that the spark & fueling is fine? Changed from cheap asda fuel to the best I could find just in case Have serviced the oil + new fuel filter Later tonight I have planned to do the following jobs: Check timing is as it should be Perform compression test Install new rotor + dizzy cap Is there anything else anyone can recommend checking? Quote Link to comment Share on other sites More sharing options...
DodgyRog Posted January 18, 2015 Share Posted January 18, 2015 You probably still have moisture in the spark plug well, N/A's are terrible for this Had it myself and I would of sworn I had dried it Strip it down, so you can get full access to the plug wells, leave the plugs in and get a heat gun. Then make sure all the leads are perfectly dry inside If you can leave it stripped for a couple of days and keep running the heat gun over each well every now and again I would also take the plugs out and check you didn't accidently tapped one and closed the gap Quote Link to comment Share on other sites More sharing options...
Mike2JZ Posted January 18, 2015 Author Share Posted January 18, 2015 You probably still have moisture in the spark plug well, N/A's are terrible for this Had it myself and I would of sworn I had dried it Strip it down, so you can get full access to the plug wells, leave the plugs in and get a heat gun. Then make sure all the leads are perfectly dry inside If you can leave it stripped for a couple of days and keep running the heat gun over each well every now and again I would also take the plugs out and check you didn't accidently tapped one and closed the gap Thanks for the tip, last time I cleaned it I used an airgun + rags to get rid of all signs of moisture, but perhaps you are right. Throttle body will be coming off tonight anyway, so I'll give it a recheck Quote Link to comment Share on other sites More sharing options...
Graham1984 Posted January 18, 2015 Share Posted January 18, 2015 Dizzy cap and rotor arm/Ht leads and spark plugs are the normal issues. The only other issue I've ever had that caused a missfire was my Mines ecu having a hissy fit. Quote Link to comment Share on other sites More sharing options...
Havard Posted January 18, 2015 Share Posted January 18, 2015 If you are satisfied that you haven't got any moisture, I would go either distributor or HT leads. Had this problem with my old NA and replacing both sorted it. Quote Link to comment Share on other sites More sharing options...
Mike2JZ Posted January 18, 2015 Author Share Posted January 18, 2015 So tonight: Checked the ignition timing and it was running dead on but problem persisted. Then changed the distributor cap & rotor arm (old one looked very worn). These two alone have made the engine more rev happy, which is nice, but it's still not perfect. Will update with further changes Quote Link to comment Share on other sites More sharing options...
Graham1984 Posted January 18, 2015 Share Posted January 18, 2015 So tonight: Checked the ignition timing and it was running dead on but problem persisted. Then changed the distributor cap & rotor arm (old one looked very worn). These two alone have made the engine more rev happy, which is nice, but it's still not perfect. Will update with further changes Check for a white colour on the HT leads/ or as Havard said would be another good option. Quote Link to comment Share on other sites More sharing options...
Havard Posted January 19, 2015 Share Posted January 19, 2015 Check for a white colour on the HT leads/ or as Havard said would be another good option. HT leads were a dear do at the time so I left them till last (£107.00 IIRC). They did fix it although they did still look in decent condition from the outside. H. Quote Link to comment Share on other sites More sharing options...
Mike2JZ Posted January 20, 2015 Author Share Posted January 20, 2015 Been a good day today, haven't done any other tinkering on the car since the last update but the misfire issue has disappeared after some driving around, have also regained power throughout the rev range. I guess the new rotor arm + cap is allowing the sparks to run more healthily and has purged anything that was causing an issue previously Will order some new leads just for good measure. For the moment, case closed Quote Link to comment Share on other sites More sharing options...
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