Blown intake manifold gasket???

[URSPANKED]

After two runs at HRP last week, the car would barely run. It was running pig-rich. Looked at it today and started it up and let it run for a couple of minutes. The headers on the driver's side were cold. I checked and had spark, pulled plug and had gas on it. Checked compression on two of the three cylinders and a couple on the passenger side. All were in the 150# range.
My son, J-rod thinks the intake manifold gasket has blown on the inside of the valley. In other words, not on the outside of the motor. Motor will not pull much vacuum, and is running very rich. There's no water in the oil, or bubbles in the radiator when the car is running. Anybody have this happen, or can suggest any other possibilities?
On the second pass, the car dropped 8 mph and it happened in the last 300 ft. of the run. I appreciate any help or ideas.

 

[Mr. T-Type]

a leaking intake gasket generally causes a lean condition

 

[URSPANKED]

But wouldn't that be true if it was leaking to the outside of the motor? We suspect that the gasket was pushed out on the side nearest the valley. In other words, the gasket would be leaking towards the inside of the motor. I sprayed WD-40 along the top of the intake gasket with the engine running and it made no difference. I also didn't mention that the car will hardly build any boost at all.

 

[novaderrik]

do you have a lot of blowby coming out of the valve cover breather under boost?

 

[GNX423]

Make sure there is not a post Mass air leak, it sound like you have all the symptoms of one. Check the pipe connections going into the turbo, then all off the intercooler connections and T-body. I split one of my connections onece and could not see it, I have also blown the pipe off a few times.
Worth taking a look.

Mike

 

[URSPANKED]

I don't know about the blow-by under boost. I'm not sure how you would see it. The car sounds like it is only running on about 2 or 3 cylinders.
I intend to reinspect all the intercooler connections, hoses, etc. The only thing that makes me want to dismiss that is that I disconnected the MAF sensor and it will normally straighten up and idle right. It didn't seem to make any difference.
I sure appreciate all the help and suggestions. These cars aren't easy to figure, are they? That's why it helps to have this board to turn to. In most cases, someone has experienced what you have and have solved the problem.

 

[ajt86]

my GN was running on 4 cylinders- one shot plug wire- and one bent push rod- it still spanked a mustang on the ride home. i got it home looked everything over found no spark on one plug wire and pulled the valve cover to see a bent pushrod- tomorrow itll go back together hopefully. the odd thing is is that my A/F ratio was perfect with the miss

 

[URSPANKED]

Anyone else have any ideas? If you would, please read all the posts on this thread, so you can get the background...not many of them. I appreciate any help you can give.

 

[87gninpa]

i had the same problem your'e having, no vacuum leaks, intake manifold was good, head gaskets were good, but car seemed to run on 4 cylinders. after replacing a ton of parts, it turned out to be the ignition module. how to test is take all of the boots off of the module and let them just rest on top. while the car is running, take one off at a time to see if it makes a differece (they all should) if any of them dont, then thats your problem. also check the ccci fuse, that could do it......dont know if this is your problem, but its worth a shot. and yes, a leaking intake will cause a lean condition and it wont cause it to run that bad unless it is an obvious leak on the outside.

 

[URSPANKED]

87gninpa,

By the ignition module, you're talking about the coil pack, right? I pulled the plug wire off the front driver's side cylinder, which had the cold header, and put a spark plug on it. I turned the engine over and the plug was firing. Should that be enough of a test, or would the strength of the spark be an issue? It looked like a pretty strong spark.

 

[87gninpa]

yes, it can mean coilpack or ignition module, one or both can be bad......i would recommend doing the test i first spoke of. this will either tell you its niether the module or coilkpack, or it definately is.....also, be sure to check that ccci fuese, they tend to go bad from time to time...

 

[URSPANKED]

Is that fuse in the under-the-dash fuse box? Also, what does that CCCI stand for? Thanks very much for your help.

 

[87gninpa]

yes, its in the fuse box under the dash....it will say CCCI right above(or under) it. youll know which one it is. it stands for computer controlled coil ignition(or something very similar) always good to check that when the car starts to run like crap out of nowhere....even after i replaced my bad module the car didint run right until i replaced that....let meknow how the test goes

 

[URSPANKED]

Finally fixed it!!!

Don't want to bore anyone, but I feel that anything we learn about these cars is invaluable. There are so many things that cause us to throw parts at them, then still don't get the problem fixed.
I have the Max Effort 16 position thumbwheel chip. The car was running pig-rich. Unplugging the MAF sensor did not make any difference, as it did when an intercooler hose had popped off. I had a 72# emissions chip and decided to put it in to eliminate a chip problem. The car idled perfect. It seems that completely unplugging the 16-position chip and plugging it back in fixed the problem. We put in the 16-position chip and the car runs great. It must have been a bad connection or something. Anyway, I hope this helps someone else.