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I sure hope some one here can help with this one.
1990 2.9 manual 4x4
my son and I were taking the trash of (don't drive truck much It's his 14 yr old) well it started running rough. I told him it deserves a good tune up so we put plugs cap wires you know the works, I say hay lets give her some new injectors while were here. well apparently no good deed goes unpunished. LOL
I did bench test the injectors before we put them in.
And now Truck will idle prefect in shop when you put it under a load it. starts misfiring horrible rough idle like can't read the valve covers, no power wont pull its self on level ground. Let it sit over night runs perfect again till you load it.
I've swapped the TFI with a used one, did the same thing.
Replaced the distributor pickup module. (cause I can't test it) (timing set 10° with spout out)
I am back probing the ECM and using a DVM
coolant temp is correct
IAC temp correct
Map sensor correct
fuel psi 32 snap 40
vacuum 20ish until it goes south then 10ish
Now the kicker (again back probed at the ecm) when it goes south the O2 sensor will drop from Average .400-.500 mv to .020-.095mv I know this is correct because I can feed it some propane and the numbers come back up and it starts running better. So I'm fairly sure it's a fuel issue. I have repeated this several times.
I can hear the injectors clicking with a stethoscope they should be working.
my question is the ecm knows it's lean why isn't it giving it fuel?
BAD ECM! no replaced it with a new one same thing (have a buddy at the parts store)
Now I haven't put a new TFI on it,
can? does it control fuel delivery I was thinking the Map and the O2 did that. that the TFI just told it when to deliver.with that being said could it not be telling it to deliver it intermediately?
If so how would I test it (oscilloscope)?
I'd appreciate any help, man talk about getting my butt kicked
Thanks Danny
1990 2.9 manual 4x4
my son and I were taking the trash of (don't drive truck much It's his 14 yr old) well it started running rough. I told him it deserves a good tune up so we put plugs cap wires you know the works, I say hay lets give her some new injectors while were here. well apparently no good deed goes unpunished. LOL
I did bench test the injectors before we put them in.
And now Truck will idle prefect in shop when you put it under a load it. starts misfiring horrible rough idle like can't read the valve covers, no power wont pull its self on level ground. Let it sit over night runs perfect again till you load it.
I've swapped the TFI with a used one, did the same thing.
Replaced the distributor pickup module. (cause I can't test it) (timing set 10° with spout out)
I am back probing the ECM and using a DVM
coolant temp is correct
IAC temp correct
Map sensor correct
fuel psi 32 snap 40
vacuum 20ish until it goes south then 10ish
Now the kicker (again back probed at the ecm) when it goes south the O2 sensor will drop from Average .400-.500 mv to .020-.095mv I know this is correct because I can feed it some propane and the numbers come back up and it starts running better. So I'm fairly sure it's a fuel issue. I have repeated this several times.
I can hear the injectors clicking with a stethoscope they should be working.
my question is the ecm knows it's lean why isn't it giving it fuel?
BAD ECM! no replaced it with a new one same thing (have a buddy at the parts store)
Now I haven't put a new TFI on it,
can? does it control fuel delivery I was thinking the Map and the O2 did that. that the TFI just told it when to deliver.with that being said could it not be telling it to deliver it intermediately?
If so how would I test it (oscilloscope)?
I'd appreciate any help, man talk about getting my butt kicked
Thanks Danny
