AMG Posted February 16 Share Posted February 16 Hi all, I have a problem with hunting idle/ stalling and would appreciated advice. So.... Drove the car fine, parked up and next time i went to it it really struggled to idle and stalled. Seems fine initially, but when the revs settle it then hunted really badly. This is what i have done so far: New battery New plugs IACV swapped for known working unit MAP sensor swapped for known working unit Checked for Vac leaks and replaced plenty of hoses for good measure. Everything i have done so far has appeared to improve the issue and on the odd occasion after rough idle and stall, it would fire up and idle perfect leaving me thinking problem solved... but no. Now it appears more obvious it is over fuelling due to the exhaust colour. No AF gauge to confirm. It does not stall now following all the changes but idles very low and still hunts. When i shut it off it struggles to fire back up again. So, what i am now thinking is the Throttle position sensor. I have not touched this at all as yet as rather do my research before i go fiddling. Is there an easy way to check to see if the TPS is knackered. Presume it is the TPS (right hand side of the TB) and not the Sub TPS (Left side). Any thoughts or advice very much welcomed. Little bit stuck at the minute. Link to comment Share on other sites More sharing options...
Mike2JZ Posted February 16 Share Posted February 16 What’s the spec of the car Link to comment Share on other sites More sharing options...
AMG Posted February 16 Author Share Posted February 16 BPU J-Spec tt. Nothing has changed with the spec for a very long time so something has failed due to wear or time. Link to comment Share on other sites More sharing options...
Mike2JZ Posted February 16 Share Posted February 16 Auto or manual? Link to comment Share on other sites More sharing options...
AMG Posted February 16 Author Share Posted February 16 Manual pal Link to comment Share on other sites More sharing options...
AMG Posted February 16 Author Share Posted February 16 The only time it has idled well and stable is when I have unplugged the MAP and the car stalls. Plug back in and idles normal. But then switch off and try again and back to hunting and over fueling. Link to comment Share on other sites More sharing options...
Mike2JZ Posted February 16 Share Posted February 16 Take engine ECU cover off and check for any blown capacitors. Super commmon that ECU's failing randomly these days Link to comment Share on other sites More sharing options...
AMG Posted February 16 Author Share Posted February 16 I will give a look. I am running a blitz access ecu. Link to comment Share on other sites More sharing options...
Big Supes Posted February 16 Share Posted February 16 Check the lambda sensor plug as they're also a tired these days and the car will struggle to recover back to idle while running rich. Best thing to do is unplug it and test to see if improves. Link to comment Share on other sites More sharing options...
AMG Posted February 16 Author Share Posted February 16 Will put it on the list the check. Was going to replace O2 sensor shortly once got through MOT. Sods law. Will have to sorn it too. Link to comment Share on other sites More sharing options...
AMG Posted February 17 Author Share Posted February 17 Today's update.... Checked the O2 sensor conception, all seems fine. During very rough over-fuelling idle i checked the O2 sensor voltage with battery ground and OX1 port and can only get a fluctuation of between 0.02 and 0.1v. Even after attempted cleaning i get the same. Maybe this could be the culprit. Time to replace the O2 sensor and see i suppose. Link to comment Share on other sites More sharing options...
AMG Posted February 21 Author Share Posted February 21 Maybe a silly question, but are the pre and post cat O2 sensors essentially the same with different cable lengths? I have a post cat sensor and wondering if I can just extend the wires. Link to comment Share on other sites More sharing options...
AMG Posted February 26 Author Share Posted February 26 Well.... O2 sensor replaced and still no better. Still struggling to idle and obvious over-fuelling. Also checked voltage via the engine Dia port and still very low readings so the port probably does not work. I get no codes or lights when bridging in that port either. Running out of ideas now. TPS next maybe? Have not touched this in the slightest in 23 years. So far replaced: Iridium plugs, MAP sensor, IACV, Most vac lines, O2 sensor, New battery Not opened the Blitz Access ECU yet but gave all wiring a good wiggle to see if anything happened, nothing. Anyone got anymore suggestions? Link to comment Share on other sites More sharing options...
Samurai 20V Posted February 26 Share Posted February 26 Have you cleaned the Idle control valve? This was the cause of the issues with idle on my car. Link to comment Share on other sites More sharing options...
AMG Posted February 26 Author Share Posted February 26 Yes mate. Cleaned it out, no better so replaced it with a known working unit. Same with the MAP sensor and Lamda sensor. Might look at the engine temp sensor next or take the ECU out to have a look at the boards. I did have my original ECU somewhere but no idea where that is these days Link to comment Share on other sites More sharing options...
Samurai 20V Posted February 27 Share Posted February 27 Only other advice I can offer is to inspect the throttle cable, I had issues with a high idle when the cable was frayed. Not sure if it can cause a low idle. Other than that, might be ECU as you mention. Good luck. Link to comment Share on other sites More sharing options...
AMG Posted March 1 Author Share Posted March 1 Well check the ECU and could not see anything obvious to me. Put it back and now it won't even fire up. Gutted. Have manged to fix the enhinencheck light soldering though, for what that is worth now. Link to comment Share on other sites More sharing options...
AMG Posted March 1 Author Share Posted March 1 ECU! Opened it up AGAIN and found these 2 caps have leaked Link to comment Share on other sites More sharing options...
Stipete Posted March 1 Share Posted March 1 Had this problem on an old skyline of mine, had your symptoms and used to misfire. turned out it was a dodgy ECU in the end. Upgraded to a link and problem sorted. Link to comment Share on other sites More sharing options...
mwilkinson Posted March 2 Share Posted March 2 Might be worth speaking with an ECU repair service to see if they can help. Quick internet search shows these: https://bluehawkelectronics.co.uk/services/ https://www.autotronics.co.uk/repair/services/ecu-repair https://www.ecutesting.com/about-us/ 1 Link to comment Share on other sites More sharing options...
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