I noticed this upon returning home with my C4 that I had purchased in Fla. and drove the 1500 miles to Mass.

http://i271.photobucket.com/albums/j...wswitch006.jpg


First a little history, while driving the temps where in the mid 90's during the day, at night, mid to low 80's. The first sign of trouble occurred while sitting in traffic (G.W. bridge *#%@^) the engine temps. began to soar ( to be expected ) and began to run very poorly, low unstable / rough idle. Once cooled down it runs better. Like many others it seems to run best during closed loop. There is a noticeable difference in idle and overall performance after reaching open loop.

I'm thinking that the combination of high outside temps. and a possible lean condition, cylinder #4, #6, or both may have caused this.

Running the stock Multecs. The injectors have been ohm tested hot and cold. Cold @ 17 ohms, Hot, three increased to 18 ohms. The static timing is spot on, 6 deg. BTDC with ESC disconnected.

I don't posses a OBDI scanner as of yet, no way to monitor BLM's. This is probably where I need to start. My winter project is to replace the injectors and a few other things.

 

I seriously doubt that injectors are the problem. Who knows what happened under the previous owner. What do you mean by "temps began to soar"? Of course it runs better in closed loop, it was designed that way. What codes do you have?

 

What temp did the coolant reach ??
That plastic loom should not be on the spark plug wires. I'm surprised only that section melted.
Sounds like you have your open and closed loop, mixed up. Starts (cold) in open loop, then goes into closed loop after a few parameters are met.

 

"Running the stock Multecs. The injectors have been ohm tested hot and cold. Cold @ 17 ohms, Hot, three increased to 18 ohms."

You wrote the above in your post. It is normal for the injector coil resistance to increase as the temperature increases as electrical resistance is a function of temperature. It is also normal for all eight injectors to increase in resistance as the engine warms up.

Only three of eight increased??? What were the hot resistance values of the other five injectors? It is possible for the injectors to all have acceptable resistance values when cold and unacceptable values when hot. If the hot readings are lower than the cold readings, the coil windings are in the process of "shorting out"!

I would recommend you check for ECM codes. You do not need a scanner to do this activity. If you have questions on checking for codes, please post this for us. Did you recall if the service engine soon light came on during your troubles?

Please post the hot resistance readings.

 

No codes present.

The needle on the analog gauge was approaching the 260 deg. mark.

My bad, Start up = open loop.

I wasn't sure if the looms were installed that way or not. Makes sense the drivers side does not have the looms

 

I would start with a thorough check of your cooling system including fan operation, cooling flush and refill if anything looks suspicious, etc.. The analog gauges are notorious for reading high.

 

That is hot. Fan(s) working ?? Look for garbage stuck to condensor and trapped between condensor and rad.

 

I'll double check for ECM codes. No SES.

The readings are as follows:

Cold Hot

#1 - 17 18
#2 - 17 17
#3 - 17 17
#4 - 17 17
#5 - 17 18
#6 - 17 17
#7 - 17 18
#8 - 17 17

Keep in mind this only occurred while stuck in heavy traffic on a very warm day and has not happened since. The current temps. are much lower now. I have checked for obstructions, none found. The fan (primary) did come on while idling in neutral, analog gauge around 230 - 240.

 

Those readings look fine. There is so much BS out there about injectors that everybody wants to blame them. My Multecs are fine and so are many others. How could injectors on 3 cylinders cause temps to spike, only in heavy traffic, even if they were bad? It makes no sense. Check to make sure your secondary fan is coming on and then proceed checking the cooling system.

 

Just to verify, no DTC present.

Both fans operated after grounding terminals A & B.

Does the secondary fan operate on a set temp. determined by the ECM or does it use a temp. switch?

I should also mention that the previous owner had replaced EGR, plugs & wires, cap & rotor. Seems to me he was chasing the same problem.

Currently the car seems to be operating in the proper temp. range, but the idle is very lopey once in closed loop.

 

In 1990 both fans are controlled by the ECM. I don't have a 1990 FSM.