Author Topic: Car Running in "Limp Mode" on Start Up (Read 24206 times)

Burnall4 · « **Reply #15 on:** September 15, 2008, 08:51:14 PM »

So my car has been sitting all day long, I know it would act up. So using the complete tool kit in my trunk

I disconnected the battery (positive side) Depressed the brake pedal (gets remaining charge out of the car) and then unhooked the ECU. Then i went and helped my friend with her car alarm that was set off for no reason and wouldn't shut it off. Come back to my car, put everything back together, fired it up rev'd it for the first min, varied the throttle....and you know what not a damn thing. I still have to test some things out but its some progress....

By chance does everyone with this problem have a chipped ECU? I do...just a thought!

AcSchnitzer318is · « **Reply #16 on:** September 16, 2008, 12:32:57 AM »

^It'll run good for awhile. Hell, mine doesn't even throw any codes anymore since I've changed all the lines and everything. I have used different ecu's to check if that's the problem. One of which from a car with no running/idling issues. Tried chipped versus unchipped just for S&G's... but of course no difference.

I'm leaning towards a sensor/bad engine ground/FPR at the moment. I've changed everything else.

Oh what is the disc shaped check valve mentioned above?... haven't changed that.

EDIT: I can't find a listing for that part number above on RealOEM or other site...

Burnall4 · « **Reply #17 on:** September 16, 2008, 09:07:37 AM »

The check valve is against the firewall on the driver side of the engine, it has a 90 degree bend with a disc/circle underneath it, separate by two hoses I will try to find a picture.

ON another note, its doing it again, ran fine all last night and this morning when i had to move my car, but when I went to work/school it started again again damn it :mad:

Burnall4 · « **Reply #18 on:** September 16, 2008, 09:23:14 AM »

Has anyone checked to see if their catalytic converter is clogged?

AcSchnitzer318is · « **Reply #19 on:** September 16, 2008, 10:30:52 AM »

I was curious about the cat as well. I am having my whole exhaust system replaced up to the header soon. New pipe, new hi flow cat, and new muffler... so I'll let you know what that does for me. Replacing due to annoying exhaust leaks.

Is the check valve the 90 degree thing in the brake booster vacuum line?

Burnall4 · « **Reply #20 on:** September 16, 2008, 10:47:10 AM »

Yes (about the check valve, location and appearance)

I am curious to know if its clogged, hmmmm...

AcSchnitzer318is · « **Reply #21 on:** September 16, 2008, 03:49:55 PM »

Quote from: Burnall4;56800

Yes (about the check valve, location and appearance)

I am curious to know if its clogged, hmmmm...

Well... I just did a bunch of work to the car. Checked the valves (both of them). The one on the booster and also the one by the carbon canister both appeared fine. I carb cleaner sprayed them and lubed them anyway. We'll see if that does anything. Was going to check the FPR but couldn't get it out of the rail. I checked the cam and crank sensor connections to the big electrical box under the intake. Also checked there were no frayed wires or anything in the box itself since I had the intake off.

Then I seafoamed it

LOL talk about smoke. I took an 8.5 minute video of smoke. I treated the oil, gas, and sucked in through the nipple that the brake booster line is normally hooked up to. After reving it for 8 minutes I drove it for about 10... not flogging it but getting up to 5.5k on gear changes to ensure I cleaned it out. In a bit I am going to go buy some new oil and change it.

On the drive getting the rest of the smoke (carbon) out... I must say the car felt awesome. This could be placebo but time will tell. Also no way to know if messing about with the stuff I checked/cleaned did anything for our start problem yet... but I'll keep you guys updated. I wanted to do the seafoam because it is supposed to clean the PCV system... and exhaust system.

Burnall4 · « **Reply #22 on:** September 16, 2008, 05:34:00 PM »

Quote from: AcSchnitzer318is;56820

Well... I just did a bunch of work to the car. Checked the valves (both of them). The one on the booster and also the one by the carbon canister both appeared fine. I carb cleaner sprayed them and lubed them anyway. We'll see if that does anything. Was going to check the FPR but couldn't get it out of the rail. I checked the cam and crank sensor connections to the big electrical box under the intake. Also checked there were no frayed wires or anything in the box itself since I had the intake off.

Then I seafoamed it LOL talk about smoke. I took an 8.5 minute video of smoke. I treated the oil, gas, and sucked in through the nipple that the brake booster line is normally hooked up to. After reving it for 8 minutes I drove it for about 10... not flogging it but getting up to 5.5k on gear changes to ensure I cleaned it out. In a bit I am going to go buy some new oil and change it.

On the drive getting the rest of the smoke (carbon) out... I must say the car felt awesome. This could be placebo but time will tell. Also no way to know if messing about with the stuff I checked/cleaned did anything for our start problem yet... but I'll keep you guys updated. I wanted to do the seafoam because it is supposed to clean the PCV system... and exhaust system.

When you test the start up let me know. I think I am going to replace a good majority of the sensors/hoses to start off with, I am about to order a bunch of stuff from pelican and bma. Which thread had the list of stuff you replaced?

ak96ss · « **Reply #23 on:** September 16, 2008, 06:40:12 PM »

Do a part-vehicle search, it shows for the E36 M42.

Burnall4 · « **Reply #24 on:** September 16, 2008, 07:29:54 PM »

Does our o2 sensor have a internal heating element or is it heated by the exhaust gas?

Burnall4 · « **Reply #25 on:** September 16, 2008, 10:40:39 PM »

ok so i played "mad scientist" tonight. I unplugged the o2 sensor and rest the ecu, leaving the o2 out of the "loop" so the ecu would not see it and the engine was as cold as ice...here is what i found out

1. the car ran for longer without starting to choke itself out
2. when the temp needle made its first move the idle changed slightly
3. as the temp needle progressed the idle got worse and worse
4. when it moved out of the blue into the black before the first white mark (on the temp gauge), it smoothed out to normal.

What does this tell me:

1. the problem is related to temp of the engine hence :warm start idle problem:
2. Check all things that are affected/effected by temp on start up, coolant temp sensor, ICV, rubber (expands and contracts)

Thoughts?

AcSchnitzer318is · « **Reply #26 on:** September 17, 2008, 12:14:29 AM »

Still does the warm start idle issue. I am still glad I did the seafoam though because now the car runs even better than before and man do the internals look clean (from what I could see through the VC). Below is my list so far... Up next is, crank/cam sensors, new cat (hi flow aftermarket) & exhaust. The more I think about it... the more I think it is the crank or cam sensor.

1. ICV (replaced)
2. Vacuum Leaks (did TB heater delete and replaced hoses)
3. o2 Sensor (replaced)
4. Plugs & Wires (replaced as part of maintenance)
5. Fuel Injectors (mustang 19#)
6. Exhaust Header Gasket (had a leak)
7. AFM (replaced)
8. Engine Temp Sensor (replaced)
9. Throttle Position Sensor (replaced)
10. ECU (replaced)
11. Intake Boot (replaced as maintenance with new motor)

Burnall4 · « **Reply #27 on:** September 18, 2008, 05:14:12 PM »

hmmmm, what is weird, is when I was in the car just a couple of minutes ago. The car started fine, it was completely hot. Then as I turned onto my street (I am leaving my parking area) the car wouldn't go...pedal all the way to the floor, car idles rough then all of the sudden bam it figures out that i have it floored and it goes like a bat out of hell.

Makes me think its the ICV and the TPS...but i keep getting this gut feeling about the fuel pressure also...this is so aggravating

AcSchnitzer318is · « **Reply #28 on:** September 19, 2008, 10:36:06 AM »

Quote from: Burnall4;56962

hmmmm, what is weird, is when I was in the car just a couple of minutes ago. The car started fine, it was completely hot. Then as I turned onto my street (I am leaving my parking area) the car wouldn't go...pedal all the way to the floor, car idles rough then all of the sudden bam it figures out that i have it floored and it goes like a bat out of hell.

Makes me think its the ICV and the TPS...but i keep getting this gut feeling about the fuel pressure also...this is so aggravating

Mine does this all the time when I am too inpatient to let it idle and fully warm up. If I just drive off (even if it appears to have started and idle properly) it will do exactly what you describe.

After doing some research... I found that my car with the original motor in it would do this exact thing. But the new motor that I put in it didn't have any signs of this problem before being installed in the car. Soooooooo this leads me to believe it is a sensor or component totally isolated from the engine. Which makes sense because none of the usual fixes worked. Are there any components completely removed from the engine/trans that could be causing this? My fuel has been checked, ECU replaced, but other than that I am at a loss. I was thinking a possibly clogged catalyst? Going to have a complete header back exhaust redo... so we'll see if that fixes it.

EN318isPDX · « **Reply #29 on:** September 19, 2008, 10:45:10 AM »

Quote from: AcSchnitzer318is;57012

Mine does this all the time when I am too inpatient to let it idle and fully warm up. If I just drive off (even if it appears to have started and idle properly) it will do exactly what you describe.

After doing some research... I found that my car with the original motor in it would do this exact thing. But the new motor that I put in it didn't have any signs of this problem before being installed in the car. Soooooooo this leads me to believe it is a sensor or component totally isolated from the engine. Which makes sense because none of the usual fixes worked. Are there any components completely removed from the engine/trans that could be causing this? My fuel has been checked, ECU replaced, but other than that I am at a loss. I was thinking a possibly clogged catalyst? Going to have a complete header back exhaust redo... so we'll see if that fixes it.

When i was dealing with my cold start issue, I thought my cat was clogged also, the easiest way to tell is to stick your hand behind the muffler, no air flow = clogged cat

Even after preforming this test about 10 times i decided to take it to an exhaust shop. They drilled a hole in my cat and stuck a sensor in it. No issues with my cat.