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Drove it another 25 miles or so today:
It seems when the engine is cold the idle is a little lower, but still rough. No smoke out of the exhaust anymore, but a slight rich smell. Better than before. Once warmed up, steady 1500RPM idle speed, very consistent.
Doesn’t seem to be bogging as much on the highway, but still getting some resistance when WOT as though it’s getting flooded out.
high idle- didn't see you mention if you tested the TPS?
Have not tested it, but I'll pull it back off and do so.
New development while driving today:
While driving, if I push in the clutch, let off the gas, and coast for ~3 seconds the check engine light will come on. As soon as I touch the gas, the light will go out. Car does not stall, but this was duplicated several times with the same actions and reactions from the vehicle. Really strange this one...
a CTS is quite easy to test. it has two pins, and there are two temp sensors in it, one pin is for the ECU, and the other pin is for the ICU, and the body ground is the common return. take it out, measure the resistance from each pin to the body. at room temp (68F), either pin to ground should be around 2300 ohms. in boiling water (212F), it should be around 200 ohms. at temps in between, the resistance shodul be in between (100F == 1300 ohms, etc)
a CTS is quite easy to test. it has two pins, and there are two temp sensors in it, one pin is for the ECU, and the other pin is for the ICU, and the body ground is the common return. take it out, measure the resistance from each pin to the body. at room temp (68F), either pin to ground should be around 2300 ohms. in boiling water (212F), it should be around 200 ohms. at temps in between, the resistance shodul be in between (100F == 1300 ohms, etc)
I believe the new CTS I was sent is no good. After I installed the new sensor the check engine light came on with codes 1-2-3 and 2-2-4. Tested it for resistance, got no readings and the sensor plug end was freely spinning inside the sender? Put in the old CTS and the CEL went out and car was back to running how it was prior.
Also discovered that one of the vacuum hoses coming from the PCV system to the intake had actually broken off the nipple on the intake hose There was enough left to reattach the hose but will probably end up getting a new new one of these as well. The plastic was rather stiff and the cold temps may have made it a little more brittle.
Seem to be striking out left and right here. Yet to pull the TPS back off and test that but it's on my list to do tomorrow.
Last edited by FantasticGarlic; Dec 27, 2020 at 03:08 PM.
Car was running a little rougher than the last few days so I popped the hood and noticed the hose that comes off the PCV/flame trap and connects to the accordion intake hose had actually snapped the nipple off the intake hose. Brand new too!? Getting a new one of those form iPd this week, however I have doctored it with a hose clamp for now as there was ~1/4" of the nipple remaining.
Taking it out for a drive today it smelled/sounded a little like an exhaust leak and I heard a rattling from underneath the car. The O2 sensor wasn't sitting quite right in the bung, was loose and rattling around inside the exhaust. Getting the old sensor out was a bit of an adventure (involving an oxy acetylene torch) and the threads weren't pretty when installing the new one so maybe there is a leak here? This would go back to what Pierce said about getting faulty O2 sensor readings; though I did replace this after the problem started initially to try and rectify it. It hasn't been an issue until now, but after tightening it a little it drove beautifully—say 80% of where its supposed to be.
On the way home, the CEL popped back on and stayed on this time. Got code 1-3-3 from pin 2—"Throttle position sensor idle setting faulty." Didn't pull it off to test today, but I am interested to see the result when I do.
Last edited by FantasticGarlic; Dec 28, 2020 at 06:40 PM.
I've got an 87 740 turbo.
i was having a similar problem with it running rich and then eventually going into a protective mode and had to limp home. Earlier in the year I had replaced the plugs, plug wires, vacuum hoses but to no avail.
Last year replaced the distributor cap and the internals the year before.
After much frustration I knew it was a MAF issue or a MAP issue so I ordered a new MAF sensor.
I let it idle for a couple minutes as suggested. I took out for a drive and all of a sudden it ran like a new car.
With 490k on it, it felt amazing..
Dont overlook this as the potential problem.
test the idle switch in place. should be 0 ohms when the throttle is at idle, and open circuit if its not. thats it, its just an on/off switch.
Originally Posted by pierce
the idle switch is the TPS, on the side of the throttle body. some cars have two switches on the TPS, one for idle, and another for full throttle.
Tested this today and got this result. 0 at idle, and OL when moved from that position. Disconnected the battery and reset the CEL, will see if it comes back on.
Also took off and readjusted the TPS to the point where it clicks. Idle is rough upon starting still and moves to a higher RPM once it is warmer, though not as high as before it seems.
Originally Posted by R2millers
I've got an 87 740 turbo.
i was having a similar problem with it running rich and then eventually going into a protective mode and had to limp home. Earlier in the year I had replaced the plugs, plug wires, vacuum hoses but to no avail.
Last year replaced the distributor cap and the internals the year before.
After much frustration I knew it was a MAF issue or a MAP issue so I ordered a new MAF sensor.
I let it idle for a couple minutes as suggested. I took out for a drive and all of a sudden it ran like a new car.
With 490k on it, it felt amazing..
Dont overlook this as the potential problem.
Replaced the MAF initally to no avail as I thought that was the initial issue.
The O2 sensor has now officially it no longer wants to reside within the exhaust . I suppose the threads from my sensor replacement can't hold on anymore, so I ordered a new exhaust midpipe rather than deal with welding on a new bung.
Car has become my daily driver again. TPS code is gone but the 1-1-3 code has returned by itself with a rougher idle. It does not smell as rich as it was when this issue initially began.
O2 sensor has been reseated in exhaust as well as a replacement of the fuel filter and fuel injectors (sans the cold start injector.) The car is now consistently exhibiting these symptoms:
-Rough idle
-Rich condition
- 1-1-3 code
It no longer is down on power or hesitating when accelerating, just running incredibly rich.
Could the cold start injector be stuck open? I attempted to clamp that fuel line while running and didn’t notice any immediate difference.
I’ll also mention that I have swapped out the pink label ECU for a white label one when I first got the car and have tried several fuel relays since the problem started with no affect.
Last edited by FantasticGarlic; Jan 17, 2021 at 01:39 PM.
Do you have any exhaust leaks up-stream of the O2 sensor? Any leaks up-stream of the sensor will allow oxygen to get sucked into the exhaust stream and cause the ECU to read that as a lean condition and enrich the fuel mixture. I use a plastic tube as a stethoscope to listen for leaks along the exhaust path.
Also check for any leaks in the air-intake system between the AMM and the throttle body. Any leaks there can cause rough idle and let it unmetered air.
Do you have any exhaust leaks up-stream of the O2 sensor? Any leaks up-stream of the sensor will allow oxygen to get sucked into the exhaust stream and cause the ECU to read that as a lean condition and enrich the fuel mixture. I use a plastic tube as a stethoscope to listen for leaks along the exhaust path.
Also check for any leaks in the air-intake system between the AMM and the throttle body. Any leaks there can cause rough idle and let it unmetered air.
I don’t believe there to be any exhaust leaks however I will try your technique and see what I find.
There was a couple small pinholes in the air intake tube between the AMM and throttle body, however I have since replaced that and that did not resolve the rich condition. It does not hesitate like it did though so I think that may be have the problem there.
I don’t believe there to be any exhaust leaks however I will try your technique and see what I find.
There was a couple small pinholes in the air intake tube between the AMM and throttle body, however I have since replaced that and that did not resolve the rich condition. It does not hesitate like it did though so I think that may be have the problem there.
I did not find any exhaust leaks that I can ascertain.
Just to bring everyone up to speed: I replaced the ECU coolant sensor again as well as replaced the TPS switch since I was getting the 1-3-3 code again.
Car runs the same (no hesitation, rough idle and rich), but now is back to only giving me the 1-1-3 code.
Ole reliable didn’t want to start today. Pulled the plugs and they were just terribly fouled—to no ones surprise. Put some new plugs in and back to where we were.
IAC appeared to be operational but ordered a new one anyway along with another O2 sensor. Going to pull the valve cover off and see if there is something erroneous under there going on. Doubtful, but at this point, why not.
There was enough left to reattach the hose but will probably end up getting a new new one of these as well. The plastic was rather stiff and the cold temps may have made it a little more brittle.
. I suppose the threads from my sensor replacement can't hold on anymore, so I ordered a new exhaust midpipe rather than deal with welding on a new bung. 
