S50 running issues

[Danny]

Agreed. I have also seen *gasp* fuel pressure regulators fail with my own eyes!!! 328icockjunkie appears to full of excellent advice today.

Danny if you're not setting any faults, I would run it with a fuel pressure gauge on it and go onto leakdown/compression from there if that didn't discover the problem. If that were caused by a vacuum leak, I think that the hiss at idle would be so noticeable that a supple young man such as yourself would hear it and quickly find a fucked connection or a cracked manifold.

I do indeed hear a hiss at idle, having replaced all the vacuum connections and lines, my woman's intuition tells me I may have a bad manifold.

[gazellebeigem3]

My 2.8 ran fine with 21.5 lbs injectors and a OBDI with stock M50b25 tune. AFR's were perfect and it had no problems getting 30 MPG. Yeah I'm sure it would of made a little more power with a proper tune, it was probably still within 95% of possible power.

My OBDI electronics must be a freak of nature because OBDI sucks sooo bad.

Agreed. I have also seen *gasp* fuel pressure regulators fail with my own eyes!!! 328icockjunkie appears to full of excellent advice today.

Danny if you're not setting any faults, I would run it with a fuel pressure gauge on it and go onto leakdown/compression from there if that didn't discover the problem. If that were caused by a vacuum leak, I think that the hiss at idle would be so noticeable that a supple young man such as yourself would hear it and quickly find a fucked connection or a cracked manifold.

[10Toes]

Never had a FPR go bad... like ever...
Your flooding out the motor big time if you dont have a chip for the 21.5's.
17's to 21's is a big jump and the OBD1 electronics will never be able to compensate for that.

And by the vid. You have a Vac leak. The RPMs drop when you open the throttle not rise immediately.

My 2.8 ran fine with 21.5 lbs injectors and a OBDI with stock M50b25 tune. AFR's were perfect and it had no problems getting 30 MPG. Yeah I'm sure it would of made a little more power with a proper tune, it was probably still within 95% of possible power.

My OBDI electronics must be a freak of nature because OBDI sucks sooo bad.

[Danny]

Doesnt mean its not leaking. Had this issue with a swap customer a few years ago. Only had ~35psi of fuel presssure at idle. Fuel line in tank from pump to bracket was leaking.

Will double check that tonight. Going to replace the fuel pump connector per FredK's suggestion.

[328ijunkie]

Doesnt mean its not leaking. Had this issue with a swap customer a few years ago. Only had ~35psi of fuel presssure at idle. Fuel line in tank from pump to bracket was leaking.

[Danny]

You replaced your fuel pump. You reuse the original pressure line in the tank? Pull the level sender out with the pump on and see if fuel is spraying everywhere.

Nope. I replaced all the soft lines with new fuel injection line.

[Danny]

The stomp test works but the whole time I haven't thrown any codes, so it wouldn't show anything. Haven't tried an ecu swap with the current issue. I have tried one when the no start issue was present.

[328ijunkie]

You replaced your fuel pump. You reuse the original pressure line in the tank? Pull the level sender out with the pump on and see if fuel is spraying everywhere.

[e30rapidic]

does your CEL work for a stomp test? ECU swap?

[Danny]

Everyone else is stumped too huh?

[Danny]

Changed the maf, no difference. Tried with the tps unplugged and it running a bit better, doesn't miss as much. Going to do a compression test on Monday. Maybe have to look into getting another m50 intake.

[ak-]

Yeah. Goodluck man.
When I said it ran fine at operating temp I meant under load.
At a stop light it would do the same annoying thing.

[Danny]

Thanks Adbu.

To update again, I let it get to temp with no change.

[ak-]

Hi Schillingster.

Again, m20 related, but I have dealt with a similar issue for over a month.
Start up, very low idle trying to correct itself.
Have to gas it or it will turn off.
Runs fine though at operating temp.
Sometimes shuts off when cruising if I let the idle drop when I press the clutch.
Happens on all start ups 80% of the time.

Just fixed this tonight and it turned out being the coolant temperature sensor.
Considering mine was bad, the ecu doesn't know the coolant/car is cold and wouldn't richen up the mixture to keep the car on.

AFR gauge at idle was 17-18 and struggling to stay idled untill warmed up.
Now, with the problem fixed, it starts cold and maintains 12-13 until warm and stoich with a healthy idle every time.

So yeah, my issue = coolant temp sensor (ecu)

[Danny]

Okay, update: Dave's piece helped a bit but not by much. Still misses really badly at low rpms and hunts a bit when idling. Not much of a change between the mad being unplugged and being plugged in.

Fred, the fuel pump connector isn't very tight and may have an issue. I will replace that Monday. Going to grab a spare maf from an awesome friend of mine and swap the good maf tomorrow. Will report back results.