M20b25 swapped, hard cold start, stalls warm unless icv unlugged

[Golfer_705]

It ended up being a faulty fuel pressure reading on the gauge when the pressure was set with the adjustable FPR. Set pressure with a new gauge and the motor now runs great. Sorry for the late reply, all the help from the forum is greatly appreciated

[Golfer_705]

Increasing the fuel pressure would tend to compensate for the lean condition that results from intake leaks. Get a smoke test run.

scotty kilmer smoke test preformed, intake leaks also check for using parts cleaner, starting fluid and propane. engine vaccume remains steady at 14 in.hg at idle

[jlevie]

I increased the fuel pressure today from the stock 3.0 bar (44psi) up to 53psi (3.65 bar i believe) Now on a cold/cool start/restart the idle will rise to 750rpm, drop to 500-550 for about 10 seconds then hold at 750rpm, smoother than at stock pressure but still rough. on a hot restart or once warmed up the motor idles at 600rpm fairly smoothly but continues to knock until the clutch is depressed.

why the continued rough start? the increase in pressure seemed to help all round with idle, it made no difference to throttle responce, mileage or driveability. what would the increase in pressure indicate with the continued rough idle on a cold/cool start/restart? how much excessive wear is increasing the pressure causing? would cause the continued knock once warm at idle until the clutch is depressed?

Increasing the fuel pressure would tend to compensate for the lean condition that results from intake leaks. Get a smoke test run.

[Golfer_705]

Fuel pump relay and connections?

relays are functioning, all electrical contacts were cleaned and inspected during the assembly

[Quinthirty]

Fuel pump relay and connections?

[Golfer_705]

update after fuel pressure increase

I increased the fuel pressure today from the stock 3.0 bar (44psi) up to 53psi (3.65 bar i believe) Now on a cold/cool start/restart the idle will rise to 750rpm, drop to 500-550 for about 10 seconds then hold at 750rpm, smoother than at stock pressure but still rough. on a hot restart or once warmed up the motor idles at 600rpm fairly smoothly but continues to knock until the clutch is depressed.

why the continued rough start? the increase in pressure seemed to help all round with idle, it made no difference to throttle responce, mileage or driveability. what would the increase in pressure indicate with the continued rough idle on a cold/cool start/restart? how much excessive wear is increasing the pressure causing? would cause the continued knock once warm at idle until the clutch is depressed?

[paperplane94]

My car stalled when warm due to a bad FPR.

It would make sense too since when you unplug the ICV, the door inside it defaults to an open position which compensates for too much fuel.

[Golfer_705]

hey, dumb question, but are you positive that the afm you have is for an i motor? I did the same swap and couldnt get it to run hardly at all when warm til I figured out that the afm I thought was for the i was actually another e... I never thought to check the part numbers...she ran great cold, then as soon as she warmed up shed start misfiring and stalling like crazy, and unplugging the ICV seemed to help but wasnt the issue...put the correct afm in her and shes been running great since

i am fairly sure that it is the correct AFM. Bosch# 0 280 202 082 (next line) 1 286615.9 The BMW salvage yard it was purchased from had it marked as a 325i in paint pen. i looked online to cross reference all used part numbers prior to installation and all seemed okay.

i reconnected the ICV and have drove another 600kms since. the idle was extremely poor cold and continued to stall hot unless revved up for about the first 200kms. the last 400kms or so i still have to keep my foot on the throttle to get the car to warm up for the first cold start of the day. on a warm restart it now idles around 500-550 roughly. on a hot restart it idles at 600-650 but knocks now unless the clutch is depressed.... no knock on a cold/cool/warm restart only the rough idle

no thing as dumb questions, all input is appreciated, please keep posting. thanks for everyones suggestions so far

[BavBeater85]

hey, dumb question, but are you positive that the afm you have is for an i motor? I did the same swap and couldnt get it to run hardly at all when warm til I figured out that the afm I thought was for the i was actually another e... I never thought to check the part numbers...she ran great cold, then as soon as she warmed up shed start misfiring and stalling like crazy, and unplugging the ICV seemed to help but wasnt the issue...put the correct afm in her and shes been running great since

[Golfer_705]

No intake leaks, all gaskets, seals, vaccume hoses, elbow replaced.


How did you test for intake leaks? I have seen many threads claiming no leaks (i.e. spraying with carb fluid), but never perform a smoke test. Please perform a smoke test if you have not done so. If there is no shop in your area that offers smoke test, you can rig one up easily (search internet) or go to www.scottykilmer.com and look up the cigar method.

Intake leaks were tested for using: parts cleaner, starting fluid and a propane bottle.

I tried the Scotty Kilmer Cigar method smoke test today, it also reveal no leaks.

All of the gaskets, seals, o-rings, hoses and intake elbow were replaced under 2000kms ago

[dnguyen1963]

No intake leaks, all gaskets, seals, vaccume hoses, elbow replaced.


How did you test for intake leaks? I have seen many threads claiming no leaks (i.e. spraying with carb fluid), but never perform a smoke test. Please perform a smoke test if you have not done so. If there is no shop in your area that offers smoke test, you can rig one up easily (search internet) or go to www.scottykilmer.com and look up the cigar method.

[jlevie]

The first think to do is to have a smoke test run and fix the leaks it reveals.

[Golfer_705]

***update***

with ICV disconnected from boot, electrical connector plugged in still, ignition on the icv vibrates back and forth remaining closed and makes a buzzing noise.

ICV connected car will not idle cold. After disconnecting ICV and warming car by holding throttle slightly open till the car idled at 700rpm (idle very rough). went for an enthusiastic drive till the coolant gauge read to 1/4 (full mark above blue) and the car idled at 900rpm quite smoothly. with ICV plugged back in idle drops to 450-500 and runs very rough. as soon as the engine temp drops under 1/4 the car stalls and will not restart unless held to at least 1/2 throttle. If ICV disconnected car restarts imediatley. Coolant temp sending unit reads 260 ohms when motor is warm and 2750 ohms after sitting overnight.

all suggestions appreciated

[Golfer_705]

The ICV operates at all engine temperatures. The fact that you stated it is not operating before cranking points towards DME to me. So it's either the DME, or the modified wiring.

It should be buzzing with the key on the on position, without cranking.

the icv is buzzing with the engine cranking, once the engine is running and continues to run after the engine stalls.

what tests are there for the DME? is there anything that could have been missed or incorrectly spliced during the motor swap?

***Correction*** ICV does operate with key on, couldn't be heard over background noise before

[Golfer_705]

Toss the adjustable FPR and install the 3.0bar FPR for an M20B25 engine. Then have a smoke test run and fix the intake leaks it turns up. Other possibilities exit, but intake leaks must be fixed or ruled out before investigating other possibilities.

The engine swap included the AFM and injectors for an M20B25, right?

adjustable FPR set @ 3bar. runs great warm with ICV electrical connector disconnected, runs a little smoother warm at idle and throttle response improved with the FPR set slightly higher though (with ICV electrical connector still unplugged). With the FPR set at 2.5bar and the ICV connected it created the same consistent rough idle that the temporarily used bosch 2.5bar regulator.

No intake leaks, all gaskets, seals, vaccume hoses, elbow replaced.

The AFM,Throttle body, TPS, Intake, Injectors, Fuel rail, harness and ecm were all pulled with m20b25 motor

With the ICV unplugged once warm the car runs great. ICV has been tested and swapped for another known good unit, it made no difference to cold or warm idle