1986 Coupe GT: Fresh Exhaust

[the german]

CIS-E Gurus, I need your help!

Just scored a nice single owner CGT, which has been sitting since 2002 and has 212k miles on the clock. It starts and idles nicely, but sputters and bogs with any throttle input. I found a CIS-E manual for the 5-cylinder quantum online, and went through the diagnostic checks to test all the inputs to the ECU and found the following items :

1. "Sensor plate potentiometer" is not giving the proper signal to the ECU (resistance values were out of the specified range by quite a bit). Looked online but it appears nobody sells a replacement part. Checked with my buddy at the local German junk yard and he doesn't have any CIS vehicle right now for me to try swapping in a different one.

2. Temp sensor was questionable

3. Vacuum advance diaphragm on the distributor is shot, so I pulled the vacuum line off and capped it

4. Lots of old rotting vacuum line, all of which I went through and replaced w/ fresh


I have the following parts on order for a tune up, all of which will be installed this weekend:
Distributor cap
rotor
plugs
plug wires
temp sensor
O2 sensor
timing belt


It absolutely seems to be a lean misfire, so I tried adjusting the DPR to richen up the mixture. 2.5 clockwise turns of the adjuster screw and the motor runs smooth up to ~3k rpm, but the idle speed dropped to about 300 rpm. I took it out for a drive, got it up to a 70mph cruise on the freeway, then all of a sudden it lost power and started running like poo again and could only do about 40 mph.


So, what is the best approach to get this thing running decently so I can drive it? Does anyone have a manual for tuning up the injection system, and maybe some suggestions of things to try?

[scubagli]

You need to get the fuel distributor cleaned, the safest way is to find a shop that has the Bosch machine that cleans the fuel distributor, also make sure the air metering plate is clean and lubed.

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[GTJeff]

Nice Score! I miss my 86' CGT which I owned for like 17 years.

On a regular CIS Lambda car like my 200 the AFM potentiometer only runs the trip computer. I don't remember what it does on CIS-E but probably the same thing.
Some things to check:
Fuel filter
Check for binding of the air flow sensor plate against the cone.
On my car there was a screen in a fitting on the inlet of the fuel distributor.
Although I never attempted it apparently the CIS-E fuel distributors are rebuildable and you can get kits for them (probably last resort).
There is a range of current that the DPR is supposed to run at idle. Maybe that manual you found explains how to adjust it.
Although is sounds like your car starts and idles well I know for a fact that CIS injectors hate to sit for very long. You might consider replacing those. I can just about guarantee it will make a big difference with new ones.

Does the ISV buzz with the engine off, ignition on? If not then first check the fuel injection fuse. I had some corrosion around it one time that caused this problem. Also check the idle (and full throttle) switch. Otherwise probably a dead ISV. You can can take it apart clean up the pitted contact points on the rotor and give it some lube but it will die again pretty soon so maybe try and find a new one.

Static ignition timing. I liked it around 12 degrees.
Definitly replace that vacuum advance.

Good luck!

Jeff

[the german]

Awesome, thank you both! I will start working through that list. One more thing- the air metering plate moves smoothly, but it feels like it is dampened quite a bit and as a result does not move quickly. Is this normal?

[AudiSport4000]

Also check the ECU ground on the side of the intake manifold. DPR (as Jeff mentions above) sounds like a good thing to test as well.

[scubagli]

No the air metering plate should move freely, I'd clean and lube it.

[GTJeff]

If the system is pressurized then the plate will have some resistance to moving up but it should always move down freely.

[the german]

got it, sounds like it needs some love then. I have lots to do this weekend LOL

[AngryTaco]

How does it run past 3k?

If idling too low, just adjust the throttle plate screw.

IIRC, but arent CIS-E cars fuel pressure controlled via a vacuum solenoid?

[the german]

It pretty much doesn't run past 3k- just starts sputtering again.

Adjusted the throttle screw, not enough adjustment...

FPR is vacuum controlled, but in stock configuration the line goes to the air box, so it's not really doing anything. I have read that routing it to the intake makes for a noticeable improvement.

[AngryTaco]

That sounds like a vacuum leak. Have the injector o-rings been replaced recently?

[the german]

Nope- pulled them out tonight to see what the spray pattern was like and flow test them. Looks like the original seals, so going to order up new ones. Hopefully that will help a lot.

The good news is that the spray pattern and flow is pretty good on 4, one has lower flow so working on soaking it in solvent and cleaning it out. Already reduced the flow delta by half! Tomorrow I'm going to try and source new seals locally, as well as install all the tune-up parts which arrived today.

[AngryTaco]

triple check for all vacuum leaks. Get a cheap cigar, and blow about 2-3 breaths into the brake boost line. Watch for smoke if you don't become high like I do

[alxdgr8]

NAPA has the injector seals. They aren't the viton ones but they work fine

[the german]

Perfect, thanks Alex!

Cigars do funny things to me too- like make my wife tell me I stink LOL

[the german]

OK- today I did the following:
-Cleaned injectors
-injector seals
-temp sensor
-o2 sensor
-spark plugs
-plug wires
-distributor cap & rotor
-swapped original DPR (@ original setting) back in
-tripple checked for vacuum leaks, capped off connections to everything non-engine related

I also checked the sensor plate movement w/out fuel pressure, and it moves freely. At the same time I adjusted it's position as it seemed to be off, however once I hooked it back up I realized that was a mistake as the position changed with the system pressurized. I tried to get it set back to it's original position, but I'm confident it's still not right.

Anyway, got the car started and running smoothly, but it's still doing the same thing as before where it bogs with any throttle input. I decided to see what effect ignition timing would have, and sure enough i was able to make a vast improvement by adjusting timing slightly.

Then, it died from idle and would not restart.

I could smell fuel with extended cranking, so I unplugged the fuel pump relay and cranked it for a few seconds- sure enough it started up, ran for ten seconds, and died. Repeated this process 2-3x with the same result. I'm thinking it is dumping fuel in to the intake and flooding the thing. My suspicion is that fueling is off across the board. What I really want to do is swap in a known good fuel distributor/metering plate and see what happens.

Any other ideas?

[AngryTaco]

back the DPR off 1/2 turn. What did you set timing too? I advanced mine a few degrees over stock

[PRY4SNO]

Any other ideas?

20vt quattro swap

[AngryTaco]

Any other ideas?

20vt quattro swap

Go back to your hole!

[the german]

ITS FIXED!!!! Picked up a known good fuel distributor & metering plate this morning, swapped it in, and it now runs great! Now to fix the rotted out exhaust..

Thank you everyone for all your help!

[AngryTaco]

Weird. Those are usually the LAST thing to fail. Glad you fixed it

[scubagli]

Weird. Those are usually the LAST thing to fail. Glad you fixed it

Not when they sit for 12 years...

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[AngryTaco]

True. I guess I didn't read that part about this coupe lol

[the german]

OK- fun new issue:

I went to change the timing belt last night (since the old one was at least 12 years old), and ran in to a bit of an issue getting everything clocked correctly. Putting the new one on, set the bottom end at TDC (harmonic balancer mark, flywheel mark, and manual check of cylinder 1 confirm it), then line the mark on the cam gear up with the notch on the timing cover and throw the new belt on. Then I checked the distributor- but found that the rotor was like 160* off from the alignment mark. WTF?

I tried rotating the cam position by 180* thinking is may have been mis-marked, adjusted the distributor to match this setting, but still not right (won't start). Finally, looking for pictures online, I found a picture from a DIY which shows the cam position WAY off from the mark on the timing cover. Using a stud for reference, I counted teeth to figure out this position and tried it- car starts but runs rough. Advance 1 more tooth and try again- car runs much better but still doesn't seems quite right. Try again, seems maybe a little worse. Took it for a test-drive and it's smooth, but feels underpowered.

Has anyone else had this experience? Any suggestion about what I'm doing wrong?

Thanks!

[AngryTaco]

Dot on back of cam gear lines up with top of valve cover gasket on driver side

The "0" on flywheel should be halfway covered by the "ledge" in the bellhousing.

Adjust the Distributor rotor to where it faces #1 spark plug wire.

Adjust timing with a timing light after starting up.