Timecode Posted June 14, 2014 Share Posted June 14, 2014 I have a 71 240z with a l28et running a 84 turbo z31 JWT ecu. My car currently shoots flames during overrun. They last for a few seconds during this time. The car runs and drives fine but the AFR's read 11-11.8 at idle, partial throttle cruising, and WOT. Every so often they jump to 14 during high vacuum but only for a split sec. JWT said check the throttle position switch and o2 sensor. I am away from home so I can't check now but thought I'd ask if anyone has had these issues before. The TPSwitch looked good last I checked and had continuity between the top two pins at idle position. I havent checked continuity at the ecu yet. O2 sensor seems correct, single wire 22mm unit. Im going to pick up a oem o2 just in case. Sounds like a loose conection to me though. Any thoughts? Quote Link to comment Share on other sites More sharing options...
Nelsonian Posted June 14, 2014 Share Posted June 14, 2014 We must have a video of this!!! Quote Link to comment Share on other sites More sharing options...
Timecode Posted June 14, 2014 Author Share Posted June 14, 2014 The only videos I have show my license plate and I don't edit so I don't think I want to post it. It is kinda cool but I'm not really proud of it shooting flames and I want to get back to driving it. I don't think the cops like flames too much. Quote Link to comment Share on other sites More sharing options...
AZGhost623 Posted June 15, 2014 Share Posted June 15, 2014 shoot it from the side of the car instead of directly from the rear. Agree we need video! Quote Link to comment Share on other sites More sharing options...
Tony D Posted June 15, 2014 Share Posted June 15, 2014 And the problem is what, exactly? Quote Link to comment Share on other sites More sharing options...
rejracer Posted June 15, 2014 Share Posted June 15, 2014 (edited) And the problem is what, exactly? Clearly the problem is it's not 4 foot flames. We need the obligatory rev video, complete with the toe shot. Wear sandals. My keen sense of the obvious is its running rich. What sensors on the JWT ecu are used to determine injector pulse width? Start there. Since the JWT ecu is a recalibrated stock ECU I assume it is still looking at the same sensors. I would check the AFM, CHTS and all grounds. From there I start wiggling wire looms, checking fuel pressure, checking for vacuum or exhaust leaks. In other words, the basics, guided by a bit of knowledge of the shortcomings of these cars. The ECU and grounds on these cars are a very common problem. The last thing I do is spend coin on parts. Replace/repair what's broken, nothing more. Edited June 15, 2014 by rejracer Quote Link to comment Share on other sites More sharing options...
Tony D Posted June 16, 2014 Share Posted June 16, 2014 (edited) "The car runs and drives fine but the AFR's read 11-11.8 at idle, partial throttle cruising, and WOT. Every so often they jump to 14 during high vacuum but only for a split sec." That's just too rich. That's Clark's safe default for on-boost, and limp-home. Get up to like 3,000 rpms in 5th gear and let your foot off the gas, coast back to 2,100 or so...note what the AFR does and report back...if you don't see evidence of fuel cutoff on decel...you're in limping home mode. Plug into the Consult Port and download the codes. It will direct you where the sensor error lies. If you hacked the earlier ECCS harness, and didn't swap ver the Z31 harness...you can ask yourself "why did I do that?" That 11:1 is your problem, it's wrong for a car at idle, it's wrong for a car at light cruise, it's wrong for decel from speed in gear. My bet is a a sensor is completely unplugged, has corroded terminals, or has an issue whereby the signal is not returned to the ECU...just like any 81-83 system. Which I'm assuming is the harness you're using since it's a 1-Wire O2 sensor and not the Z31 Three-wire (why bother with the ECU swap if you retain an unheated sensor!!!!????) Swap a 30 year old ECU into a hacked 31 year old harness: "some upgrade"! Welcome to the first logic steps towards true standalone--and proper harness rework! Good Luck! Edited June 16, 2014 by Tony D Quote Link to comment Share on other sites More sharing options...
Timecode Posted June 16, 2014 Author Share Posted June 16, 2014 I bought the car with the swap completed already. I'm just discovering the truth about what I truly have, parts wise, because the owner who sold it to me had no idea about the build. It was the owner before him that did the major work. Had I'd known that my computer came from a 84 I might have reconsidered the purchase. Ill try to get this setup working right before I go to standalone I think. It does go like stink still. I'll check the stuff you guys mentioned and post back. Quote Link to comment Share on other sites More sharing options...
Tony D Posted June 16, 2014 Share Posted June 16, 2014 "because the owner who sold it to me had no idea about the build." I'm sure you realize the Sarcastic Reply to that is self evident! LOL 84 or 88, it really doesn't matter--retention of the earlier harness, without the ability to use the diagnostic function really kind of hamstrings the easy way to go about this. Quote Link to comment Share on other sites More sharing options...
Timecode Posted June 29, 2014 Author Share Posted June 29, 2014 ^ Not everyone that owns a Z knows everything about them. If the build was done 2-3 owners ago I think some info missing during a sale is to be expected. Plus who has a week to analyze the car they are about to purchase. Nobody is born with Z experience...except maybe you. Got to start somewhere. Quote Link to comment Share on other sites More sharing options...
Tony D Posted June 30, 2014 Share Posted June 30, 2014 "Plus who has a week to analyze the car they are about to purchase." A well-seasoned car buyer who doesn't want to waste months or perhaps years fixing someone else's abortion. You seem to have done well buying in Haste. Try it my way next time and you could be driving trouble-free right now! As you kinda said "Live and Learn"--this is one of those times. Choose to learn from the wisdom laid down or don't. I don't care one way or the other, it's your money and your time! You obviously have more of both than I do! Quote Link to comment Share on other sites More sharing options...
m1ghtymaxXx Posted June 30, 2014 Share Posted June 30, 2014 And the problem is what, exactly? My question too. If everything else checks out, I would embrace the flames! +1 on a video! Quote Link to comment Share on other sites More sharing options...
Tony D Posted June 30, 2014 Share Posted June 30, 2014 We are 'not being helpful'... An ounce of prevention... Quote Link to comment Share on other sites More sharing options...
NewZed Posted June 30, 2014 Share Posted June 30, 2014 (edited) Any thoughts? Maybe the PO installed super-duper 440 cc Supra injectors to go with the JWT modified ECU. Lots of different ECU's under the "JWT Z31" category. A lit of part numbers will help you out in the long run. Know what you're working with. http://www.jimwolftechnology.com/customer_results.asp Here's something useful - http://jimwolftechnology.com/wolfpdf/280%20Z31%20450HP%20UPGRADE.PDF Edited June 30, 2014 by NewZed Quote Link to comment Share on other sites More sharing options...
Timecode Posted July 1, 2014 Author Share Posted July 1, 2014 (edited) I'm a little surprised by the responses here. I come to this site often and the comments are usually helpful. Tony, get off the high horse man. You are our Guru. You shouldn't be schooling people on their car purchases. Telling people how to buy a car is good and all but I don't have enough time to learn EVERYTHING about every different car I buy. Was I suppose to ask the guy for a hundreds of photos so I can pick apart the car? I could barely get 15-20 good pics of the car from him. Turbo Z's get picked up quick and he didn't have to jump through hoops with me. He could just wait for the next local guy.I shopped and saved for 5 years for my Z. Never planned on buying one with an L-series engine. Found a super nice one. Flew to Minnesota from SoCal to buy it (had a free flight that was about to expire). The guy had people lined up to see it.. I got the car for such a good price, including shipping, it would have been a good deal with no engine at all. I also wasn't going to stay there for a week or wait for another couple years so I jumped on it. Anyone would have. Forged l28et with a Version 1 JWT kit, suspension, LSD, a turbo axles, the list goes on an on. I think I'll try and make this setup work. Thanks Newzed for the links but I am familiar with Jim Wolfs sites. I did say it was a 84 ecu or would you like the part number?. You'll notice no info on there site about this because it was an older version of there kit. I've been talking to Ben there, smart guy, and he's trying to help me figure it out. Says its a really old version but its still good. It had 420 cc injectors instead of 440cc. The MAF was a Z31 unit instead of the current Ford unit. They switched due to the Z31 units dying from the flow demands. I hope that's not the case with mine. Rejracer, I will need to check on the things you mentioned. The o2 is working and I have continuity at the ecu. TPS is working and I have continuity at the ecu. So next are the things you mentiond. Not sure if I'm misreading people but if the belittling can stop this thread could actually turn into something useful for others one day. Edited July 1, 2014 by Timecode Quote Link to comment Share on other sites More sharing options...
Tony D Posted July 1, 2014 Share Posted July 1, 2014 The biggest thing to learn is take your time buying a car and these types of situations will be avoided. If you think this is "belittling" people, you indeed have some issues that go beyond rationalizing the purchase as you seem intent on doing. All you may say may be true. Then again, maybe there was a reason it was priced "so good"! Impatience and Imprudence go hand in hand, it's only through frank assessment in retrospect will you learn that lesson. Carry on, have fun, keep us posted on what you did to get it running. I will watch intently. I think the thread has actually turn into something useful for others ... The first line of this post is the wisdom to take. The progress of this thread is the validation of that lesson. Quote Link to comment Share on other sites More sharing options...
NewZed Posted July 1, 2014 Share Posted July 1, 2014 Thanks Newzed for the links but I am familiar with Jim Wolfs sites. I did say it was a 84 ecu or would you like the part number?. You'll notice no info on there site about this because it was an older version of there kit. I've been talking to Ben there, smart guy, and he's trying to help me figure it out. Says its a really old version but its still good. It had 420 cc injectors instead of 440cc. The MAF was a Z31 unit instead of the current Ford unit. They switched due to the Z31 units dying from the flow demands. I hope that's not the case with mine. No need for the part number. Just pointing out that JWT Z31 ECU could be one of many possibilities. Even 84 turbo has four model numbers. Also implying that there is no guarantee that the PO knew what he was doing. People install large injectors all the time thinking that more gas = more power. And there's no way to notice no info on the JWT site for your older ECU because it was never said that it was an older out-dated ECU. It's not apparent that you've been on the site, or actually talked to someone at JWT, you didn't say. It looks like you have more information than you've shared. Post it up. Not many people talk about the JWT products, they're a mystery even though they've been around for a while.. The O2 sensor is only really in play during cruising conditions. Probably not the cause of your flames. Quote Link to comment Share on other sites More sharing options...
Timecode Posted February 4, 2017 Author Share Posted February 4, 2017 (edited) The issue was an intermiten TPS. It would test fine on the car even after it was set correctly but after a short time down the road it failed. Little strange because after I set it, I opened and closed the throttle a bunch of times it still tested fine, started it up and a short drive later it failed again. I didn't open it up to see what was wrong because I had a spare that I threw on and it worked. So if you suffer from this issue don't trust your TPS 100%. I found I wired my wideband incorrectly so my reading were false. Sorry for the late response, figured this might help someone one day. Edited February 10, 2017 by Timecode Quote Link to comment Share on other sites More sharing options...
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