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Hi Van,
Its a 1989 chev 5.0 TBI...will idle in open loop but stall from idle when in closed loop. NO codes set.new fuel pump,idle air,tps(set to .56mv),ecm temp sensor.tryed a good map...checked vac hoses(ok)..checked PVC(ok new)will idle in back up fuel?have OTC2000 scan tool. I am lost! almost feels like spark loss? run fine down the road! rpm gets down to 575 it stalls.
Thank you very much!
Tom Woolf
Answer -
Hi Tom,
Have you cleaned the EGR valve? If it seats on a piece of carbon, it is just a big vacuum leak.
Van
Hello! Van,
Ok i checked and cleaned the EGR(was real clean) new gasket.No help. replaced the TBI gasket No help. still to me acted like it was loosing spark.took the dist module and had it checked failed to low RPM test! Great we found it! NO! put a new one in and the same thing! still no codes and if i put it limp mode(backup fuel) it idles and you can put it in gear. something I see on my scan tool is that there is no injector pulse? tried two modes...and shows no advance? could it be the ECM is not getting a the pulses?(bad coil,wiring,ECM)?There is two plugs on the coil what do they go to?(ecm?tbi?) I got a e-mail saying the coil is going bad? what you think? and one saying the pickup.. the truck starts right back up.if you hold the idle at 900+ it will run but die in gear. it will die in Open loop if you put it in gear or use the power steering. where do i look now?
Thanks so much Van!
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Hi Tom,
I still would like to know what the fuel pressure is, with the engine running.
It has got to be 13PSI or so.
6 PSI will run, but not worth beans.
There is a fuel pressure regulator on the throttle body.
Check also the distributor shaft, to see if the bushings are worn out.
Van
OK fuel pressure is 14 at idle. the bushings are fine.checked the ohns on the pick-up 850 ohms(cold) The pick-up is super rusty.I am going to check the output at cranking speed. I think it should be around 500mv AC.I was told if its to low the ECM will loose the Low REF. and to check it hot when it starts stalling. ohms and output. Thanks Van! what now? what would you check next? also have a good coil to try! No Vac leaks! it will idle in limp mode.(back up fuel) could the oil sensor do this? engine heats up oil gets thinner bad switch opens telling the ecm low oil pressure? Just guessing at this point..gauge shows 25 hot idle gauge never shows more than 35 cold.. Thanks again your a great help!
AnswerHi Tom,
There is no oil sensor signal to the ECM.
The oil pressure switch just runs the fuel pump whenever oil pressure is above 4PSI, as a backup system to the fuel pump relay.
Your fuel pump system sounds great.
Don't suppose you have access to a complete distributor you could stick in there to try?
Then there is the ECM itself.
Van
