calpoly-z Posted May 23, 2009 Share Posted May 23, 2009 I've been helping a buddy of mine put a 83 turbo motor into his 74 and after facing innumerable little issues we finally have her running great at idle and cruise. The engine is pulling close 20" at idle and it will rev fine under low load. As soon as you try to get on the throttle though the car just falls flat at around 3500 or so. today we drove around with a boost guage and despite all our attempts we were unable to reach positive pressure either. I've set the TPS to spec and timing is at 20 BTDC. Injectors have been cleaned and flow tested and fuel pressure is good. The motor is fresh from the machine shop and most everything is either new or rebuilt, except for the turbo which may be suspect. We are using the factory ECU and harness for now, but the plan is the go MS in the future. Any help would be greatly appreciated. Thanks guys Quote Link to comment Share on other sites More sharing options...
Arif Posted May 23, 2009 Share Posted May 23, 2009 Have you checked the wastegate? It might be stuck open and not allowing the turbo to build up any boost. Quote Link to comment Share on other sites More sharing options...
KunoZ Posted May 23, 2009 Share Posted May 23, 2009 Also pull the intake hose off going to the to turbo and see if the compressor wheel isnt damaged. May have accidently droped something in it while doing the swap and chewed the compressor wheel up. Just a guess. Quote Link to comment Share on other sites More sharing options...
RUZN Posted May 24, 2009 Share Posted May 24, 2009 Yeah , jammed Compressor or turbine unit, something not on even though you think it is. or wastegate totally stuck open. Otherwise as long as you have Exhaust pressure you should get boost. Quote Link to comment Share on other sites More sharing options...
calpoly-z Posted May 24, 2009 Author Share Posted May 24, 2009 Even if the waste gate is stuck open the car should just behave as if its N/A. It won't have a lot of power, but it should still run and drive fine. Right now I'm leaning towards a messed up compressor wheel that is choking the engine under heavy load or something like that. I remember checking out the turbo and noticing it had a bit of shaft play, but I don't recall either wheel looking messed up. We'll check that next though. If I feather the throttle I can get the car to rev past 4k so the problem seems to be load related. I don't know if it matters, but there is no exhaust on the car yet. Just an MSA downpipe. Thanks for the ideas and please keep them coming. Quote Link to comment Share on other sites More sharing options...
hughdogz Posted May 24, 2009 Share Posted May 24, 2009 Have you checked to make sure the turbo's oil feed line is not blocked? The drain line could get blocked too, but it is ~3/4" so that seems less likely. Try blowing some compressed air through it to see if it can flow freely. I've seen it recently, where they suspected the turbo was bad, but it was really a completely blocked (used) oil feed line which caused the shaft to completely shear in half. Hope this helps.. Quote Link to comment Share on other sites More sharing options...
xxjoeyxxeb Posted June 7, 2009 Share Posted June 7, 2009 So we checked out the turbo yesterday and it spins freely and the wastegate is not stuck open. We drove around and played with the fuel pressure gauge and the fuel pressure regulator and hoping that the fuel pump is not keeping up with the engine. Ordered a walbro 255 and will keep ya'll updated. If that doesn't fix it, we will be back. Quote Link to comment Share on other sites More sharing options...
HowlerMonkey Posted June 7, 2009 Share Posted June 7, 2009 Restricted exhaust maybe. Or........you have a sensor issue. Quote Link to comment Share on other sites More sharing options...
xxjoeyxxeb Posted June 7, 2009 Share Posted June 7, 2009 There's only the MSA downpipe on it. We can try to go over the sensors I guess. Already swapped out AFM, going to swap out the coil to my Blaster 2. Quote Link to comment Share on other sites More sharing options...
HowlerMonkey Posted June 7, 2009 Share Posted June 7, 2009 I've seen someone use ultra black rtv on the rubber boots over the tps harness and it caused the car to think the throttle was at idle all of the time because it conducts electricity. Quote Link to comment Share on other sites More sharing options...
VinhZXT Posted June 8, 2009 Share Posted June 8, 2009 How about just clean and reseat the connectors at the ECU. When it bogs it usually a fuel issue. If you have good fuel pressure then it's the ECU not getting info from the sensors and/or AFM. Therefore the ECU doesn't send signal to the injectors. GL Quote Link to comment Share on other sites More sharing options...
xxjoeyxxeb Posted July 31, 2009 Share Posted July 31, 2009 UPDATE Still doing it. Got a new turbo, installed the Walbro fuel pump. And it's still sputtering when it gets heavy load into boost. FPR is from a working car, injectors flowed on our test bench. Will try swapping out the coil this weekend. Also have MS ordered. Quote Link to comment Share on other sites More sharing options...
loy Posted July 31, 2009 Share Posted July 31, 2009 I've had a similar problem with my car, it turned out to be the way my afm was mounted. The connector on the afm should be about facing the driver side of fender wall. Hopefully it might help. Quote Link to comment Share on other sites More sharing options...
xxjoeyxxeb Posted July 31, 2009 Share Posted July 31, 2009 Really?! Right now I have mine turned probably 90degrees so the connector connects on the top of the AFM. I wonder if that is messing the the flapper? I will try to rotate it tonight and let you know. Strange... but thanks! haha Quote Link to comment Share on other sites More sharing options...
skib Posted July 31, 2009 Share Posted July 31, 2009 I've seen it recently, where they suspected the turbo was bad, but it was really a completely blocked (used) oil feed line which caused the shaft to completely shear in half. oops that one was me the stocker runs for about 30min with a plugged feed line, then it shreds itself to bits lesson learned, always check your feed lines I have my AFM with the plug facing strait up and dont have any problems Quote Link to comment Share on other sites More sharing options...
xxjoeyxxeb Posted August 2, 2009 Share Posted August 2, 2009 UPDATE We changed the AFM direction and had the same problem. So we decided to check the timing again and it was still holding a constant 18-20 deg we set after multiple starts and short drives. But when given throttle, the timing would go down to about 8-10 deg then slowly go up to about 15 deg when held at 3000 rpm for about 10 seconds. Any ideas why it would be doing this? The main things that have not been changed out are the distributor and ECU. Thanks Quote Link to comment Share on other sites More sharing options...
HowlerMonkey Posted August 4, 2009 Share Posted August 4, 2009 Does it act exactly the same with the airflow meter disconnected? Quote Link to comment Share on other sites More sharing options...
xxjoeyxxeb Posted August 4, 2009 Share Posted August 4, 2009 Have not checked that, but what if it did? Quote Link to comment Share on other sites More sharing options...
JSM Posted August 4, 2009 Share Posted August 4, 2009 Did you check the plugs? Also are you sure you have a good connection at the Water temp sensor and your not flooding out? Did you unplug and clean the ECU as VinH suggested? I had a similar problem and it was the connection on the ECU. Actually drive it and have a buddy wiggle the connection on the ECU. See if it does anything. Also check and recheck all your grounds. Quote Link to comment Share on other sites More sharing options...
luvmy280zxt Posted August 5, 2009 Share Posted August 5, 2009 Might look kinda strange if you are driving and a buddy wiggles it...lol Other drivers might think.....well you do the math. LOL Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.