Chrysler 2.5 TBI. Intermittent bogging/timing/idle?

[nszotovich]

Please don't take the car up to 95 mph. You are not doing the car any good. The car was designed for 55mph speed limits that were in effect then. Driven gently, K-cars can give you many years of reliable use. Red line driving will only hasten its demise. If you do want to get 300K miles out of it, you should be treating it with a little more reverence.

[MyDodgeDip]

Well, the 2.5L DID come with vacuum light. My memory fails me again. Thanks for the correction.

I suppose with 7 cars I should specify which one that's a picture of That's on my 86 reliant wagon with a 2.2/Manual 5 speed. I was just posting it for reference so people knew what it looked like.

[89ARIES]

Yes, that was stupid. I rarely did that. I also am puzzled why weather, wetness, and what not makes my max uphill speed at a certain spot
on the freeway vary on a day to day basis. Say, 77mph one day and 81mph another day. And then, sometimes I get more cruising speed by not flooring
it and just gently massaging it.

[89ARIES]

Well, the car is still not quite right. It is bogging a lot when cold now, sometimes warm. I don't understand, good compression, starts up right away, no check engine light, etc. It is also
still ocassionally bucking on the freeway, and the idle is still a little rough. Can a brake booster really cause engine driveability problems if it has a leak? Anyway, here is what I was thinking of
trying:

Dropping the gas tank for the first time in 23 years and getting it cleaned out.
Running some powerful Lucas Gas Treatment.

As for the bucking, it seems to be entirely related to the rough idle. The smoother the car runs, the less likely it won't buck. So, all along I assumed the bucking was electrical, but could
that be ruled out now since the engine computer seems to be functioning perfectly? Could it really have been a combo electrical/mechanical that caused my car to die that night when it had several
codes and the computer didn't work for 5 mn?

[K-CAR_WAGON]

good compression,

Did Butch actually check the compression recently for you the last time that he worked on your car and patched the bad wiring - in which case he would have removed the plugs and seen that they are currently in good condition - and not fouled? Spark plug wires ok or recently changed? Spark voltage level checked at the individual plugs or on a scope?

Dropping the gas tank for the first time in 23 years and getting it cleaned out.
Running some powerful Lucas Gas Treatment.,

Fuel pressure measured by someone? Does injector spray pattern look normal to someone who knows what to look for?

[89ARIES]

The plugs looked good. We did not do a compression test or hook up any vacuum or gas gauge.

[88 aries]

"The plugs looked good. We did not do a compression test or hook up any vacuum or gas gauge."

I thought you said your compression was good. this proves that you didn't check for compression.

[89ARIES]

The scanner said 20 vacuum, which would be good. Other than that, we didn't do those two things.

[89ARIES]

Oh, the car is set at 14 degrees right now, instead of 12. Does that means it retarded or advanced? Does that make a difference?

[K-CAR_WAGON]

The scanner said 20 vacuum, which would be good.

When Butch said that the vacuum was 20 inches at idle and that he thought the engine was still in good shape, I had assumed he used a mechanical vacuum gage connectled to intake manifold and not only looked at idle vacuum but looked carefully at the response to the vacuum gage to various changing conditions to further verify everything in the motor is basically sound. You have continued to say that compression is good. Maybe, a good throrough evaluation of vacuum using a scan instrument can be done, but I suspect checking it with a mechanical gage is better. I think, when you are using a scan instrument, you are relying on a sensor and/or computer within the car to convert the vacuum level to a voltage level. Potential sensor error/conversion errors can occur depending upon how the conversion is being done and the condition/range of the sesnor in your car. It might be fine for measuring a steady state value, but I am not not sure it is best for looking at dynamic changes/responses to view subtle problems. (Maybe I am wrong and professional mechanics don't bother with mechanical vacuum gages anymore.) Sometimes a direct analog instrument readout is better than a sampled or averaged digital readout.

As for the compression being good I don't know why you did not bother to measure the compression when you had the plugs out to check for both level and balance between the cylinders.

However, in general, it sounds like Butch got you car basically running and he seems to feel the engine is basically sound. Can't you just hire Butch or someone else competent that he might recommend (in your local area - there has to be someone competent willing to work on your car) to spend some time running some diagnostic tests (verify spark is ok, - move on the fuel items, like check fuel pump pressure and delivery rate, check throttle position sensor carefully over its full range for dead spots or just change it, test map sensor or just change it, check fuel pressure regulator, check injector, check and/or just replace AIS motor, check pattern of injector spray, maybe clean/rebuilt the TBI etc.). Then, just change whatever is supect. (Most of the potential parts that might be failing are not that expensive. )

Stop worrying about the basic timing setting. Butch just set it. If you have timing problems it is probably becasue your instantanewous timing setting is being set improperly by the computer in response to some sensor prbolem. On the older cars variations in timing over a dynamic range was controlled by a vacuum advance and mechanical advance as part of the distributor. On you car, the dynamic timing curve is controlled by the computer (using a look-up table) and setting timing in response to sensor inputs. I think the timing curves mapped into the computer were less than ideal to start with since the models were rather crude in compariosn to what is done today. Someone with the appropriate scanner/logging device might be able to record what your computer is actually setting the timing dynamically as you are driving the car to see it it looks normal or looks like it is jumping all over the place. (I am not sure if this is an available output from the computer on your car.)