Jon Hansen

First post here guys.
92 C2 cab with 37k. Had my DMF go out late last fall. Go to Dealer or buy a 2 post lift for shop and DIY?
Bought lift, of course. A good winter project for Michiganders.
Did new DMF, plugs, valve adjust, new belts, new pwr strng belt and seals, tensioner gaskets, ft and rear main seals, distributor belt, strip and refinish engine sheet metal, clean and detail, etc.
Now all back together and it's running rough at idle and quitting. It seems to rev up OK, but it's not quite right, and smells rich. I'm trying to get a loan on a diagnostic tool as the check engine light goes on and off. (source to buy one cheap?)
She ran perfect before the clutch went out.
I did new caps and rotors about 2k ago, and never moved the wires during the engine out process.
Is it possible for this engine to run with the distributor in 180 off?
Any other advice would be appreciated. I'm mostly a body shop restoration guy.
thanks!

jimq

Welcome. First post should have a picture of your car attached
if its running rich maybe check the O2 sensor to be sure it is hooked up correct and is actually working.

Indycam

https://rennlist.com/forums/964-forum/412250-back-together-again-but-have-a-hick-up.html

Geoffrey

Not possible to run the engine with the distributor out 180 degrees, but I would check to ensure that the 2 rotors are aligned correctly. The rich running might simply be an out of time engine on one bank of plugs.

altarchsa

Sounds like a dist. out of line to me.

Jon Hansen

Just pulled both caps and aligned crank pulley to Z1 mark; both rotors are pointing exactly to the correct location. I marked them before doing distributor belt, and also referenced the timing sticker.
The distributor is correct. With the toothed drive belt, one of them would be way off. Any thing else I can check before I get my hands on a diagnostic tool?

altarchsa

Even though you say you did not disturb the plug wires, you had to at least bend them to get the caps off. I would check continuity of the wires. I don't think those 18-20 year old wires hold up during any movement.

I just replaced coils and wires and couldn't believe the effect they had on performance. Mine were disturbed by my top end job.

chris walrod

Check all of your connections including the MAF connector and cyl head temp sensor. I recall someone metioning some time ago about a bulletin talking about MAF connector troubles and their pins pushing out of its socket upon reconnecting the MAF sensor. May be worth a look.

Jon Hansen

Still haven't solved my rough running problem. Since I don't have a diagnostic tool yet, I decided to get a little old school to figure it out. Put the car up on my 2 post lift and Fluke temperature probed the same exhaust stud nut from each cylinder while the car was idling. The results were very interesting. Cylinders 2 and 6 were about 120f cooler than the other 4. Hmm? We talked it over and decided that possibly some crud had gotten loose when I changed fuel filter with engine out, hanging up these 2 fuel injectors.
Pulled all injectors, and first confirmed the solenoids were working. Gently wire brushed ends, sprayed Gunk carb and injector cleaner into each one, fired it with a 9v battery, and then used about 100 psi compressed air to purge. Repeated purge process about 6 times. They all seemed good from the beginning, releasing a fine mist for the most part. Reinstalled all injectors with new o-rings. The Porsche dealer wanted $5+ for each one. My local auto parts store crossed over a GM o-ring which worked great. Did all 12 plus had 2 spares for only $8.00
Reassembled, checked for leaks, and fired it up again on the lift. Same results with the temperature proble as before. Nuts on cylinders 2 and 6 are running about 120 F. cooler than the other nuts.
The car starts right up with out backfiring, surging, hunting, and idles at about 860rpm. It revs up, but seems to run rough with shaking at idle. Connections at MAF were good. This was my first valve adjustment, but I am sure I did it correctly.
Any suggestions or pointers would be greatly appreciated!

buck_31

My engine was running rough at idle after my rebuild, turned out that I had forgotten to tighten one of the hose clamps on the intake for cylinder 6 so I had a slight vacuum leak. I disconnected the coil for the bottom plugs and then with the engine running I removed and replaced each upper spark plug cable one at a time (at the plug) listening for a change in the idle. When I removed #6 there was no change, so it wasn't firing/making power properly. Found the leak and now she runs great. Not sure how safe this was but I remember doing on my first car about 25 years ago and I'm still here...........

chris walrod

You may wish to pull the valve covers and double check you didnt get a valve or two too tight.

Dual dizzy belt ok?

Colin 90 C2

there is a service bulletin for the maf connector.
Look to see if there is a tie wrap near the connector tying the wire in a loop.
I'm sure Jason can provide the TSB.

dfinnegan

See Post #4

darth

Jon

Mist the wires with water (i.e. especially around #2 & #6) and view them in the dark while the engine is running - check for sparks. Even if you don't see sparks,if they're half as old as the car they likely need replacing. Continuity of the wire is not what you're most concerned with (i.e spark plug wires have a certain resistance value per foot spec) but more importantly the insulation which must contain the hi voltage and direct it to the spark plug.

Hope this helps
Bill
90C2

Jon Hansen

Problem fixed!
Chris Walrod had the correct diagnosis. A compression test showed I had valves in 2 & 6 too tight. I readjusted using the front and back side method. Re checked compression after the adjustment to confirm. 180 to 190 psi in each cylinder.
It's running great now.
Thanks for pointing me in the irght direction Chris!