m20 stroker stumbles and quits (long, help)

[billybobjoseph]

I had that problem too. If you do have to replace it make sure you get a Bosch one. When this happened to mine it didn't cause it to die however, otherwise I would assume one of the many things that can make a car run rough when hot. I think I would do what the above guys said and if nothing works, compression test it cold then compression test it when warmed up and hope to hell the readings for each cylinder are the same both ways.

[billybobjoseph]

PS, if you do try this be careful not to burn your fingers.

[NC325iC]

this will be on the list, but in my head it doesnt really make sense. If it were going to be an internal problem coming on by heat i would expect it to be pretty gradual, whereas the car runs fine and then all the sudden it just stumbles and dies. im starting to think its some electrical thing its just figuring out which it is. I am still gonna test the exhaust next. then i will likely replace the coolant temp sender and do alot of electrical tests.

[NC325iC]

just gonna list a few things im looking through here

with coolant at approx 75 or so degrees (ambient temp) blue sensor reads 1700 ohm btw 2 poles, brown sensor read 666ohm btw pole and grnd

Injector harness on engine side has only 6 pins (pin 3 is empty) while injector side has 7 pins

all relevant (not ac test) tests on bentley fuel system page 49 completed with good results

thats all i have for today, basically no new information

[nando]

nothing abnormal about the harness. for some reason, BMW put both wires on the gauge cluster coolant temp sensor, even though the sensor only has one wire and only one wire goes into the car. don't worry about the brown sensor anyway, it's only for the gauge. The blue sensor is the important one.

I'll have to double check my calibration of the ECU temp sensor, but that value doesn't set any alarm bells off in my mind. You should also check it at a colder temp if possible, and if you could at 90c. those might require removing the sensor, putting it in boiling water, freezing, etc.

[jlevie]

The thread title say stroker, but in the first post you say that the engine has:

stock i exhaust barring stromung muffler
stock i intake manifold and throttle
Miller PSIK and war chip with tune

I assume that you mean that it has:

I head, intake, throttle body, fuel rail, & injectors
I engine harness and DME
stock i exhaust barring stromung muffler
Miller MAF & WAR chip

The first thing I'd suggest is to revert to the I AFM and chip. That will pretty quickly tell if the problem is related to the Miller parts. If the symptoms are still present in that configuration I'd check the fusible link, replace the main & fuel relays with new parts and try a different DME. The symptoms don't sound to me like an problem with the exhaust so much as they sound like an engine management issue.

[Kershaw]

could be the o2 sensor. it only comes into play after it fully heats up, which may be a few minutes if its just idling.

[nando]

it's actually closer to 30 seconds or less. the O2 sensor has a built in heater element, it doesn't rely on exhaust temperature for operation.

[NC325iC]

Alright,

The stroker was built by Pete McHenry, he gave me some limited info on it after it was purchased. It is bored and stroked to 2952cc with a late model m3 crank (i assume s50). Forged ultralight pistons, tool steel thin wall pins, low drag rings with oil ring support, "mildly" ported head (i head), schrick 284/272 dual pattern cam. All ignition components (except coil) are new stock replacements that i purchased from blunt. The coil tests out to be .8ohm primary and 5.38kohm secondary. fuel injectors are used 19# design 2 units in the stock fuel rail. FPR is a ireland engineering unit. ECU is a stock 173 with the WAR Chip, the engine harness is a slightly modified '89 i harness (modified per miller instruction to provide 12v to the MAF, and modified to be used in an 86 325e body). The intake manifold is stock i running gear, as is the throttle body. Throttle switch tested out fine in idle and part throttle with some inconsistency on the WOT switch. The exhaust manifolds are stock, into a stock cat which i purchased used from a junked car. o2 sensor is a wideband o2 from plx, output from the wideband to the ecu is a converted narrow band signal. I unhooked this output from the ecu when the problem first occured and the motor died quicker.

I just started it up and it idled for a couple minutes then gave up, didnt even get out of the blue this time so i dont know if its even temp related anymore (unfortunately i wasnt really eyeing it i was chatting with someone).

[billybobjoseph]

Can you take off the cat and try to start it like that? It'll be really loud and piss off the neighbors but maybe it's plugged.

[NC325iC]

just conducted one last experiment for the day.

alright so like i said i just ran it and it died, and like ive been saying the fuel pressure has been fine the whole time. I was thinking maybe i should test the fuel pump flow rate. so i went and i fired it up with the relay in place still, it fired up and ran (a bit rough), i then pulled the relay while it was running, it smoothed out a little bit after a second or so and then as the pressure dropped it died in the same way it has been.

does this tell us anything? perhaps its getting too much fuel causing the computer to over compensate? i dont know i just thought the results were interesting.

[billybobjoseph]

I think the thing that matters is the pressure. The brain tells the injectors when and how long to remain open and is calculated using the pressure the rail is supposed to have in it. If the flow rate was too high the FPR would open to maintain the correct pressure in the rail. If the flow rate was too low you'd have problems because you'd never reach the correct pressure.

[billybobjoseph]

Unless it was SO high the pressure built up in the rail even with the FPR open but I can't imagine your pump doing that. Bentley says disconnect the fuel return line from your FPR and put another line in it's place leading to a container. Jump (fused jumper) the 30 and 87 plugs where the relay plugs in and run the pump for exactly 30 seconds. Should give you a minimum of 875 ml or 30 oz. No maximum value is given.

[NC325iC]

forgive me, i was raised an e30 vert guy. What is this fusible link?

i will put an afm and stock chip in if i cant find another solution soon, im reluctant because it would require some un-rewiring, or another engine harness.

The thread title say stroker, but in the first post you say that the engine has:

stock i exhaust barring stromung muffler
stock i intake manifold and throttle
Miller PSIK and war chip with tune

I assume that you mean that it has:

I head, intake, throttle body, fuel rail, & injectors
I engine harness and DME
stock i exhaust barring stromung muffler
Miller MAF & WAR chip

The first thing I'd suggest is to revert to the I AFM and chip. That will pretty quickly tell if the problem is related to the Miller parts. If the symptoms are still present in that configuration I'd check the fusible link, replace the main & fuel relays with new parts and try a different DME. The symptoms don't sound to me like an problem with the exhaust so much as they sound like an engine management issue.

[billybobjoseph]

Ah right, verts have the battery in the engine compartment. The legendary fusible link is on the smaller of the two positive battery cables, under the carpeting about a foot or so from the battery in the trunk - it's usually 50 amps.