zx_drift Posted February 21, 2010 Share Posted February 21, 2010 Hey, I've recently swapped a turbo engine into my 1982 280ZX. Its been a long process, and I have almost everything figured out except that once the engine goes into boost (0 psi manifold pressure) the car starts misfiring like crazy. Also, it will not idle unless I hold my foot on the gas. The car runs fine when its cold (except there's no boost) and the same when it warms up, but for a small range, I'd say 60 to 70 degrees celcius, it misfires a lot and it struggles to stay running. I've hooked the car up to a dyno and a wide band, and its super lean except when the throttle shuts between shifts. I've checked out everything I can think of, so if there's anyone with a lot of experience with the turbo L6's, your help would be greatly appreciated. Quote Link to comment Share on other sites More sharing options...
FlatBlack Posted February 21, 2010 Share Posted February 21, 2010 (edited) Hey, I've recently swapped a turbo engine into my 1982 280ZX. Its been a long process, and I have almost everything figured out except that once the engine goes into boost (0 psi manifold pressure) Sounds like a vacuum leak and/or your VCM [Vacuum Control Module] is disconnected or bad. It's a black circular thing on the 'spark plug side.' I had a friend with a turbo 280ZX, his VCM came unhooked and he was having the same problems. If it's not running at idle, look for vacuum leaks and make sure your Idle Air Control is working properly. Also, if you're not getting over 0 PSI that means you don't have any boost, and something is unhooked or open. Go look around to find that leak. Edited February 21, 2010 by flatblack280 Quote Link to comment Share on other sites More sharing options...
zx_drift Posted February 22, 2010 Author Share Posted February 22, 2010 Isn't the VCM the device that is near the AFM? Controls EGR and AAV? I've hooked it up to a smoke tester, found no leaks. Quote Link to comment Share on other sites More sharing options...
83turbo280zx Posted February 22, 2010 Share Posted February 22, 2010 Isn't the VCM the device that is near the AFM? Controls EGR and AAV? I've hooked it up to a smoke tester, found no leaks. yes it is, he's probably referring to the vacuum canister for the ac system, check for a crack in the air flow meter boot going from the afm to the turbo, those crack and cause big air leaks and cause problems like you're experiencing. Quote Link to comment Share on other sites More sharing options...
FlatBlack Posted February 22, 2010 Share Posted February 22, 2010 yes it is, he's probably referring to the vacuum canister for the ac system That's not what I was referring to. It's on the spark plug side, not the intake/AFM side. This is a VCM I had when I was thinking about doing a ZXT harness on my swap. Quote Link to comment Share on other sites More sharing options...
zx_drift Posted February 23, 2010 Author Share Posted February 23, 2010 That thing is all hooked up. Also another symptom is the car is really hard to start when it is even remotely warmed up. Misfires like crazy, like its heat soaked. Quote Link to comment Share on other sites More sharing options...
stravi757 Posted February 23, 2010 Share Posted February 23, 2010 Im getting the feeling that there is more than one thing wrong with your car. It not starting after warmed up sounds like a bad ground to me. As for it running lean, have you checked fuel pressure, your injectors, vacuum leaks, timming, sensors, AFM ect. Quote Link to comment Share on other sites More sharing options...
zx_drift Posted February 23, 2010 Author Share Posted February 23, 2010 The injectors are new, the fuel pressure was low but I just installed a walbro 255 and now it is up at a good level. Fuel filter is new. Smoke tested intake, found no leaks. Check all the sensors as far as I know as per the FSM (MAF, ECT, TPS). Most of the FSM refers to using the ECCS analyzer. It is impossible to acquire one of these, but I have tested the sensors with a multimeter and output tests. All seem to be within the correct range. I just don't know what else to look for. I don't wanna throw parts at it but it seems like I have no choice. Quote Link to comment Share on other sites More sharing options...
FlatBlack Posted February 23, 2010 Share Posted February 23, 2010 (edited) If you can't get over 0 PSI, it's very obvious you have a leak somewhere. Is there a boost gauge in the car? How are you "smoke checking" the intake on a turbo? I don't have T-Clamps on my IC piping so I blow off the charge pipe that comes off the turbo fairly regularly, I'd check the connections on your J-Pipe. Edited February 23, 2010 by flatblack280 Quote Link to comment Share on other sites More sharing options...
BleachZee Posted February 23, 2010 Share Posted February 23, 2010 When I did a turbo engine swap, I had the same issue for a long time. It ended up being the injector holders/o-rings. The non-turbo metal style from an S30 would seem to be sealed but did not under boost. I changed them later to the full plastic style from the 280ZX and they sealed up fine and the car suddenly ran good under boost. Quote Link to comment Share on other sites More sharing options...
madkaw Posted February 24, 2010 Share Posted February 24, 2010 I would take the vcm and all the components out of the system and see how it runs. Soundslike the AAC valve is stuck open so you have an internal vacuum leak. I don't run any of those components and my car idles fine. It would probably idle good when cold, but it sounds like something is stuck open to atmospheric air Hey, I've recently swapped a turbo engine into my 1982 280ZX. Its been a long process, and I have almost everything figured out except that once the engine goes into boost (0 psi manifold pressure) the car starts misfiring like crazy. Also, it will not idle unless I hold my foot on the gas. The car runs fine when its cold (except there's no boost) and the same when it warms up, but for a small range, I'd say 60 to 70 degrees celcius, it misfires a lot and it struggles to stay running. I've hooked the car up to a dyno and a wide band, and its super lean except when the throttle shuts between shifts. I've checked out everything I can think of, so if there's anyone with a lot of experience with the turbo L6's, your help would be greatly appreciated. Quote Link to comment Share on other sites More sharing options...
zx_drift Posted February 25, 2010 Author Share Posted February 25, 2010 I smoke tested it with a tester, into the intake manifold, with the throttle plate open (so smoke would flow into the j-tube and to the turbo) I have new plastic injector clips/holders. The AAC has an idle adjustment on it, but when I turn the screw, nothing changes. Could this be because it is open? I need to have it connected because of stupid smog, but otherwise I would take it off. Also, my air regulator, the thing with coolant lines and a some temp sensor in it, is from a non-turbo z. Could this affect its operation? Quote Link to comment Share on other sites More sharing options...
FlatBlack Posted February 25, 2010 Share Posted February 25, 2010 I smoke tested it with a tester, into the intake manifold, with the throttle plate open (so smoke would flow into the j-tube and to the turbo) If I read that right, with the motor off you blew some smoke into the intake mani to check for leaks? But your problem is under boost? Get a torch, start the car, then open up the valve [without lighting it] and put it near all of the potential places it could be leaking. If you hear the car run better, it's a vacuum leak, and you can try and pinpoint where it is. I was installing a fuel rail one time and a injector O-ring popped off without me seeing it, which caused the car to run like crap. Are you 100% sure your new injector o-rings are all there? Quote Link to comment Share on other sites More sharing options...
zx_drift Posted February 25, 2010 Author Share Posted February 25, 2010 I'm positive all of the injector o-rings are there. I will try the lighter thing. But no boost isn't the only problem. It also doesn't idle, and it misses a lot on decel (clutch engaged). Seems like there are multiple problems here, and I think some of it may lie in the controls attached to the intake manifold ie. air regulator and aac. Quote Link to comment Share on other sites More sharing options...
madkaw Posted February 25, 2010 Share Posted February 25, 2010 What I would suggest would be to disconnect the octopus(see pic) on top of the intake and cap all vacuum lines and see how she runs. Between the AAC and the vacuum port valve behind it you have some large internal vacuum leak possibilities. This would eliminate the whole VCM system and you could truoble shoot from there. Don't forget the EGR too. I don't run any of these items, but I don't have inspections to worry about. The biggest issue that I have is a slight surge at idle and that's seldom. I'm positive all of the injector o-rings are there. I will try the lighter thing. But no boost isn't the only problem. It also doesn't idle, and it misses a lot on decel (clutch engaged). Seems like there are multiple problems here, and I think some of it may lie in the controls attached to the intake manifold ie. air regulator and aac. Quote Link to comment Share on other sites More sharing options...
zx_drift Posted February 25, 2010 Author Share Posted February 25, 2010 Could someone post pictures of their stock intakes and engine bays so I can compare to see how everything is supposed to be hooked up? I'm pretty sure mine is all correct, but I didn't have much reference so I could have something wrong. Quote Link to comment Share on other sites More sharing options...
zx_drift Posted March 5, 2010 Author Share Posted March 5, 2010 So I'm pretty sure my AAC is bad, I applied vacuum to it and it seems to flow air whether its closed or open. I'm going to replace it, and it should solve my idle issues, and maybe some boost problems. Anybody here have one I could purchase? I'm having trouble finding one. Quote Link to comment Share on other sites More sharing options...
madkaw Posted March 5, 2010 Share Posted March 5, 2010 I tried to PM you , but can't get that to work. Glad to hear you nailed down the issue, I thought it might be that valve. I have one off of my car that looks brand new that I will sell for 25$ plus shipping. You can e-mail me sfinnerty@indy.rr.com if you need it. So I'm pretty sure my AAC is bad, I applied vacuum to it and it seems to flow air whether its closed or open. I'm going to replace it, and it should solve my idle issues, and maybe some boost problems. Anybody here have one I could purchase? I'm having trouble finding one. Quote Link to comment Share on other sites More sharing options...
VinhZXT Posted March 5, 2010 Share Posted March 5, 2010 Too lazy to type. PM me or call me and I can help you solve ur problems 215-880-9557. Vinh Quote Link to comment Share on other sites More sharing options...
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