I've tried to search before asking this/these questions and while I've seen some answers that were close, nothing was able to quite help me fix the problem.
Here are the symptoms: I start the car, sometimes it is a hard cold start (seldom a hard hot start), the runs fine (awesome throttle response by the way) until it reaches 'operating temperature' or roughly 80 on the temp gauge. Then shortly afterward, regardless of whether I'm under power or coasting/stopped, the car stalls. I can put it in neutral and almost always start it tight back up, sometimes it takes two times but it always starts right back up. I can drive for a little while longer and then it stalls again. This just started happening. At first, it was occasional now it happens ALL of the time. I noticed that the aux fan (the one in front of the radiator NEVER comes on (but then again, the temp never gets that high before it stalls). I've replaced the alternator, battery, spark plugs, dist. cap and rotor. I've become friednly with a local MB repair shop - Marina Benz - they say it's not fuel related. This seems true since I never have problem with the throttle (and most times it starts right up).
So, does anyone have any ideas on what to check next? Where to look (besides doing another search)? I've checked the connections on the 'cooling sensor' - they were bad but I cleaned them up and the above still happens.
I would really appreciate any help on this - thanks!
I've pulled the fuel pump relay - car stalled right away.
I've pulled the black rectangular relay (forget the name now), took off the cap - it looked brand new, connections look good as well.
I've pulled the OVP, the fuse inside needed to be cleaned so I did that. I started the car, pulled the relay - the RPM's went up slightly - then I plugged it back in and the RPM's went back down again - to roughly 650 - 700 RPM.
I've also tried to adjust the air/fuel mixture technique that Jayare seems to recommend. I was sensitive with regard to the turns - tired a bunch in each direction and it still stalled.
Thank you for the response. I appreciate your advice but do you mind telling/explaining to me why you think that that's the problem? Or what and why you think I need to replace the OVP? Could I test it by taking it out and then seeing if the car stalls? If I took it out and the car still ran but stalled, what should I check next? Do you think that this would be a good test to see if the OVP is indeed the problem?
i'm not sure if it the OVP but from all the threads that i have read before in this forum thats the reason i suspect it is th eOVP.
also now if you do what you said about removing the OVP and check the car for stalling and ended that the OVP is good then i would say maybe your fuel pump is going bad thats why when it is hot gets stalls.
did you check when the car stalls that you have feul delivered to the engine?
So I pulled the OVP with the car running - it still stalls.
If I understand your question correctly, the car still stalls while I'm on the gas (like the freeway for example). Further, right after it stalls, it starts right up and then continues to run for a few minutes. So I'm not so certain it is the fuel pump. Also, the previous owner replaced the fuel pump about a year and a half ago.
My guess would be the coolant temp sensor. The engine temp information from this sensor is sent to the ECU and the ICU. This is the last sensor on the engine, closest to the windshield. It could either be a 2 terminal or a 4 terminal sensor. The resistance across the terminals should be between 2.5K and 3.5K when cold and between 250 and 350 ohms when at 80 degC. For a 4 pin sensor, check the resistance across diagonally opposite terminals. The exact values may be slightly different, but the resistance should drop by a factor of 8 to 10 when engine temp changes from 20 deg to 80 deg C. The ECU adjusts the air/fuel ratio using the temp information and the ICU adjusts the timing.
I guess, the other possibility is a defective crank position sensor. The defect shows up at higher temps.
Also when it stops, does it stop like turning off the ignition switch or does it turn off after an irratic engine output ?
Thank you for your response. To answer your question, when I'm driving there is no warning whatsoever - the car just dies. One minute, I'm driving down the road with no problems, the next minute, either I press the gas pedal and nothing happens or the dash lights come on. There is no sputtering, no vibrating...or anything really.
I was thinking it might be the coolant temp. sensor too but, as I'm sure you're well aware, 'throwing parts' at a problem is really not the way to go - or atl east it hasn't been so far - hahaha.
further, there is really no pattern to as to when the car cuts out. Well at least not after it warms up. What I mean is, the car doesn't really stall with increased frequency as I drive. Almost completely random.
strange.
As far as the crank position sensor, the engine temp never really goes above 80 c at all. I mean it has, briefly in the past, but for the most part, it is slightly lower than that juat about all the time. So, with the crank position sensor, would this be an issue at a higher temp. than 80 c? I ask because, from what I undertand, this part is not cheap.
Oh, what does the coolant temp sensor look like? I thought it had two connections coming out of a brass fitting.
You are perfectly right, replacing parts without testing is really a big waste.
I dont know if you tried this: short the terminals in the fuel pump relay socket that correspond to fuel pump relay pins 30 and 87. Use a thick short wire, around 8-10A will flow thru it. Drive around like this for a while and see if the problem is gone. If it is, then you need a new fuel pump relay. If problem occurs, it is in a place other than the fuel pump relay.
If the problem persists, then bypass the OVP relay for a while. Same pins for this relay also, 30 and 87. Caution: But before doing this, make sure that you do not get more than 14V on the battery terminal for all RPMs.
Linear Mode
