b25, manual, and m42 rad done but some issues/questions

[Supratreo]

hey guys, so finally doing the b25 w/ manual swap on my cousins 87 E and some question.

1. we decided to do the m42 radiator while we were at it and i know its hard to bleed but i don't know if thats the problem or something else. it starts to over heat if we drive it but while bleeding at idle it goes right up to the red but not over. it seems like the t-stat is not opening because the lower hose stays cold. the temp on the motor side of the housing is about 180-200 and the other side gets to about 180. new t-stat and i made sure to break the seal so it doesn't stick.

2. next is a driveability issue. if you open the throttle too fast it will hesitate/bog before it revs or if you let off too fast after WOT it will drop the revs too low and not be able to recover. this driveability issue was also present with the b27 motor. at that time we thought it might be a fuel issue so we replaced the filter but that did not seem to help. right now i'm leaning towards a fuel issue again but all that is left is the pump.

the motor, harness and maf are all from the same donor car. motor has been refreshed with all new gaskets and injectors were cleaned before install. i also opened the TPS and cleaned it. could it be that its not adjusted right? from what ive read, it sounds like you just need to make sure the idle switch and WOT switch is calibrated since theres not in between.

one last question. we have a 173 ecu, the battery is dead so we have to jump it every time, is it possible that the ECU is being reset when we shut the car off? does this ecu even have a memory or is it too old for that?

sorry for the long read but any help would be much appreciated.

[Supratreo]

also, could someone enlighten me on the fuel system? looking at ECS it seems like this car came with 2 types of pump setups, external (looks like a bosch 044) or internal. i know this car has an external one next to the filter along with a second FPR which i guess came on the 87s. as of right now i have both FPRs, could this be a problem? could i eliminate the one by the filter?

[Bimmerboy91]

On your #1 issue, I would look at that thermostat. Very likely stuck closed. Possible that it might be installed backward too.

On issue #2 have you checked fuel pressure? Also I would also suspect a malfunctioning maf. Is there any smoke out of the tailpipe when it's bogging down? Any abnormal smells?

[Supratreo]

Thermostat shouldn't be stuck, I checked it before install and it only goes in 1 way. I believe there was also a mark to show top. Worse case I'll just replace it anyway. Could it be that it's not actually over heating and it's just an incorrect reading? I'm still using the E cluster.

Haven't checked fuel pressure yet but hopefully tomorrow. No weird smells and no smoke at all.

[Supratreo]

So fuel pressure looked good at 40psi at the rail and doesn't drop. Its a little bouncy, maybe 2-3 psi but engine and fuel did not act up. It did hesitate/stumble under quick acceleration.

We also confirmed that we installed a Hella thermostat.
I'm stumped. I was certain it was a fuel issue but now I don't know. Maybe I will monitor it for a little while and we what happens.

[Supratreo]

another thing that just popped up. we installed a 85 I cluster and the gas gauge randomly jumps around a little bit but not all the time.
also did a stomp test and got 1444 which means no codes. i was kinda hoping there would be something to work off of but no.

[Bimmerboy91]

Just throwing out some ideas.

Possible loose ground or connection at the c101 plug? Ecu?

[Bimmerboy91]

The jumping around could be loose connections on the back of the gauge

[Supratreo]

Thank your for the reply.
I read about the fuel gauge issue and I'll address that tomorrow.

Are there any grounds Other than the 2 grounds that go by the passenger side strut tower? I have the one on the I'm pan which I replaced with a new one I made. Thinking about also adding one to the head.

[Supratreo]

so i have some new findings.
the nut on the fuel gauge was missing for some reason, replaced that and all seems fine now.

opened the AFM cover to see if anything looks damaged that would cause a hesitation, found nothing. inside looked brand new.

i installed another ground from the head to the battery tray and it actually seems like it runs a lot better. didn't drive it too much but it did feel good.

as for the fuel issue. the gauge is very erratic between 40-45 psi. does not stay steady. with the return line pinched pressure jumps up and stalls the motor. with the vac line off, static pressure jumps up about 5 or 10 psi, cant remember.

any ideas?