Just recently took my 87' Fiero DOHC swap out for a maiden cruise. Under accelerating through 1st, 2nd, and 3rd it will sputter and stall sometimes cutting out completely. If I give it a minute it will refire however it continues to repeat the same process. It idles fine other than the fact it will stall after 2 minutes or so.
The engine is primarily stock minus a custom intake and 13 degree camshaft retard. I had a chip burnt for it also that has (or is supposed to) have provisions for the camshaft retard.
Like Gall said, sounds like a fuel problem. Can you hook a pressure gauge up and see if you're losing pressure when this happens? How's your pump, pickup, screen, filter situation? Could be sucking in some garbage and killing flow.
------------------ 1986 SE Aero coupe.
3.4 DOHC swap is complete and running, now just have to finish the rest of the car...
[This message has been edited by tesmith66 (edited 05-21-2015).]
Check the polarity of the two wires from the crank position sensor (on the side of the engine, not the hi res one on the pulley end) that go to the ignition module. When did mine, I extended those wires (they were yellow and purple) because I moved the module and it would idle fine but had no power, cut out, spluttered etc. Somehow I had connected then in reverse when I extended them. Swapped them over and it was fine! Only took me 18 month to find that. It could well be something else but if you've touched those wires I'd give them a check, maybe even just swap them over for the hell of it just to see if it helps or not as it does not cost anything other than a but of soldering of the wires or you can repin the plug if you can get them out.
------------------ Anything I might say is probably worth what you paid for it, so treat it accordingly!
... Unfortunately it wasn't the fuel pump. Although there has been improvements! The car will start every time after it stalls if I re-prime it and the sputtering and stalling under acceleration is now gone.
Long story short, it revs fine, and starts fine. The only issue now is it will idle fine momentarily (1 minute, 30 seconds, 2 minutes, it varies) and then just cuts-out. Any thoughts why?
The factory DOHC injectors aren't very good and are known to cause some stalling (when lifting the throttle while coming to a stop) when they get old. I replaced mine with Ford yellow tops (OEM 5.0 V8 injectors) and my stalling problem went away. I do get a surging idle and some stalling when I first start the car after hooking up the battery, but after it warms up and relearns everything it is fine. Are you getting it up to temp and letting it get into closed loop operation? Sometimes you have to drive it a bit.
I got a used set of injectors on ebay for around 40 bucks.
Ford yellow top injectors you say? That's good know, thanks!
I heard that before. My current injectors are stock rebuilt units from wide open throttle technologies so hopefully their not faulty. Tonight I'm going to test my injectors, unfortunately I can't test the spray pattern easily so it will be difficult to tell if one is clogged but I will check for voltages. I'll also take it for a drive perhaps and see if the computer just needs to learn.
I've allowed it to get up to temp a few times however I could only do that by resting the pedal at 2000rpm otherwise it would stall. After I get it up to temp and return the pedal to rest position it'll run at idle for anything between 30 seconds and 2 minutes before stalling.
But it will always refire now and rev fine through the rpm range, at idle is the only place it will stall.
It might be worth mentioning I have shortened intake runners and plenum.
When I did mine and was having all sorts of problems I sent my injectors off the Rich Jensen at http://cruzinperformance.com/ to have them flow tested and checked.
Cost me around $32 back in 2004. Looks like he's still there so it might be worth while getting them tested properly.
------------------ Anything I might say is probably worth what you paid for it, so treat it accordingly!
Connect up your fuel pressure gauge. Make damn sure it isn't leaking. Tape the fuel pressure gauge to the back window so your assistant can see it. Take the car out for a drive and recreate the problem. What does the fuel pressure do when this problem occurs?
A defective throttle position sensor can also be a cause the problem that you are describing. Have you done a scan of the PCM? If your engine is OBD1 that ECM can be scanned too.
------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Flotech Afterburner Exhaust, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, HP Tuners VCM Suite. "THE COLUSSUS" 87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H " ON THE LOOSE WITHOUT THE JUICE "
Thanks for the help guy's, my fuel gauge during cruising is reading at 45-ish psi at the fuel rail. I've since replaced my tps and that doesn't seem to be it either. I borrowed TunerPro software for OBD1 of a buddy so I'm gonna try and get that linked up. Wish me luck!
Unfortunately I wasn't able to link up the scanner however I'm doing what I can do get that sorted. Meanwhile I'm checking my sensor wiring.
Prior to replacing my tps sensor I noticed all the wires going into the 3-pin weatherpack connector (voltage, ground, signal) had the insulation fried off and the wires were exposed. When I replaced the sensor I crimped on a new weatherpack connector. Would the tps wire's shorting out indirectly cause a potential issue?
Also, I started it with the IAT sensor unplugged and it seemed to idle at more consistent revs and for longer durations. Not sure if that could be an issue? However I think it might be worth checking at this point. Here in Northern Alberta Summer is short, it's desperation mode!
Another issue I should've REALLY mentioned earlier is that it is difficult on warm start-ups, although cold starts it starts fine.
Hopefully I can connect the computer soon!
[This message has been edited by Squeaky (edited 06-20-2015).]
Unfortunately I haven't been able to connect my TunerPro software so in the midst of my computer confusion I'm back on the sensor train replacing everything of unknown condition or origin, so far this has included:
She still won't idle though, I'm thinking perhaps of replacing the IAT sensor also. I'm also wondering if maybe I should also replace the O2 sensor? Since doing all the above I noticed today it idles at just passed 1000 revs for 2-ish minutes and then idles down around 500-750 revs for another 15 seconds or so before stalling. I'm wondering if once the O2 sensor reaches temp that it goes into open loop and stalls, is that possible?
Haha well I'm glad your enjoying it! Wish I could say the same, just in the midst of researching how to somehow keep my engine running in closed loop. (Someone with advice or who know's how is welcome to respond)
Only 3 solid months of nice cruising weather left after what's been a 4 year project, I may just bite the bullet and empty my pockets at a mechanics shop.
I successfully connected the scanner and was able to perform a scan yesterday evening. I couldn't load the bin file for the 3.4 DOHC so I tried the scan again after loading a 3.1l bin file. As expected it indicated that I was running rich however it also came up that my electronic spark control module was faulty, placed another one on order, just awaiting it's arrival.
