96 Buick LeSabre trouble starting

[alwerdt]

I have a 96 Buick LeSabre, good condition, 94K miles, oil changes every 2K miles. It all started when transmission fluid leaked into the upper intake manifold. I had no problems before this. My car stated accelerating at 3500 and I couldn't drive it. In this time span, I started to have trouble with the car starting. After replacing the TPS and manifold, the high acceleration stopped. But the starting problem still continued. To get it to start, I would have to give it gas or the car would die (not maintain idle). But the weird thing is it will start 50% of the time normally and not start the other 50%. For the times the car won't start, I turn the key and the car revs to about 700 rpm like it wants to start, but it won't turn over (unless I give it gas). So on days where it won't start, I have to drive with two feet to maintain the idle.

Also, no error codes are on the mechanic's computer.

Please help! Thanks!

I have replaced the manifold, spark plugs and wires, checked the alternator, battery, checked the fuel pump, cleaned the fuel system, water pump, flushed the transmission system and now run green, and the TPS. (Some of this related to manifold problem).

[maxwedge]

Well I assume you meant coolant got into the engine, not TF? Look for vacuum leaks around the throttle body, make sure you have both seals around the pcv under the maf in the manifold, spray carb cleaner in suspected areas of vacuum leaks. Scan it for proper coolant temp sensor readings also, especially cold. Did you clean the IAC and egr when this was done?

[alwerdt]

Yes coolant leaked in. Thanks.

[HotZ28]

The transmission has a vacuum modulator to help control the shift points. It has a diaphragm inside of it that will develop a leak and will cause the shifting to become erratic. Look for the transmission modulator on the front drivers side of the transmission. There is a vacuum line running to it. Pull the line off and see if any transmission fluid runs out. If it does, you have a bad modulator and it needs to be replaced. This is the only way transmission fluid could get in the intake. When the diaphragm is leaking. it also causes a vacuum leak to the engine, causing erratic idle, missfire and starting problems. Your plugs and manifold sensors (MAP) are probably coated with transmission fluid also.


When you remove the modulator there will be a short steel rod going into the transmission. This serves as an adjustment for the shift points. There are several lengths of rods available for adjustment. You shouldn't need to change it, just make sure you don't lose it and make sure you put it back in. FYI... the longer the rod, the higher the shift point, the shorter the rod, the lower the shift point.

[HotZ28]

Ok, now it is coolant!! I will just leave the above post so that you know transmission fluid can also enter the intake through the modulator!