does the 305 tpi engine in the 87 z-28 have a switch that would cuz the engine to cut out at high temp? My car runs around 200 and then immediatlly shuts off. I can't restart it for about ten minutes. I've replaced the ecm, ignition coil, back flushed the coolant system, replace the fluid, cleaned the system, and even replaced the thermostat (correctly) yet it still runns hot and cuts out. any help at all would be appreciatted. All i've been able to do is replace my car part by part. I've performed a diagnostic, and nothing showwed up. Also, the over heat light doesn't pop up. And when the engine shuts off, the electrical power isn't interuppted at all, for example, my cd-player keeps on playing, however, my engine does not!

[This message has been edited by wplax26 (edited 08-24-2001).]

Does it crank and not start? I would check and see if you have spark while the engine cranks. If it has spark than its probibaly a fuel issue. Have you replaced the fuel filter on a regular bassis? You dont happen to have the readings taken from the engine diag.?

No, i wasn't able to get the readings. In retrospect, i can't imagine why i din't ask....In any case, it's extremmely hard to test for spark b/c the problem doesn't happen in a way that i could test that. Is there any way to test for spark on the side of the road? I can tell you this, i can tell if it will restart because the tach will jump and then the engine will start, if it won't start, the tach will not move whatsoever. hope that helps

OK, latest devolpment. My car had the problem again today, and i was lucky enough to get a hard code. It was 33, which is the mass air flow sensor. Should i replace the sensor? Could the malfunction of this device make an engine cut out? and furthermore, how come it's only come up now? (the problem has persisted majorly for a month, and minorly 3 months b4 hand.)I have had a code about 3-4 times b4, but was unaware on how to check it.

A bad maf will not stop the car from running, it would only run bad. The next time the car stalls turn the key to the run position and see if the check engine light comes on. Its normal for check engine light, brake light, abs light and srs light to come on when the engine is of with the key in the run position. If the light fails to turn on then check the computer ground and power supply. Also pull out the ign. fuse and ecm fuse to see if they are failing.

My gut tells me you might have a bad chassis ground. Also is there any static noise when you listen to the radio. RF interfernce can cause the computer to shut down.

If you still cant find the problem than email me at Joekool1234567@aol

You say the tach doesn't move when it doesn't crank. You're losing RPM reference which in my experience has always led back to grounds or ignition module/pick up. I'd about lay money on the module. P.S. 200 isn't running hot

TPI gm cars dont have an external module. Its part of the computer. The only thing in the dist. is the magnetic pickup and they usaully just fail outright.

there is no static, but why would a bad ground cause a problem? I've checked the fuses and they are great. I understand 200 isn't hot, it's just that i have a 165 thermostat and furthermore, that is when i have the most trouble

Now that you reminded me that you just did the thremostat I think one of the computer grounds is on the thremostat housing. I think two or three seperate ground wires attach to the stud on the thermostat housing. Check those real good its not uncommon for them to brake when you loosen the lock nut to change the stat.

See a semi-bad ground will work ok when the car is cold but will progressively get worse as the engine heats up. You say you have to wait ten minutes before it will start agian and that is a classic example of excessive resistance do to heat and bad connection.

There is an ignition module inside the distributor that might be bad when it gets hot. There is also a pickup coil in the dist that can go bad and be heat related. the wire in the coil is thinner than a hair, very fragile.
There is an Ohm spec for the pickup coil.
There is a tach lead in the wiring harness on the passenger side of the distributor. If you put a testlight on that lead and a ground and then can crank the engine when it has quit running, and look for a flashing light. No flash means the module or pickup is bad.
Try the light on it when the engine is cold so you will know what to look for.
David

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