A couple GOOFY problems...

[kevans]

Hey Guys,

First off, I have a couple of cars with the same strange miss problem. Both cars have set ups similar to the sig below with one having ported iron heads. The car with stock heads seems to miss at high boost (25+ lbs) and DS shows that they are single frames at 18.2 fps. They are NOT MAF related as the MAF does not fall out as it used to with every miss. The ported iron head car does the same thing but at any boost level. DS shows on both cars the injectors being turned off for a single frame and then coming back on line. LV8 seems to be the most common variable to cause the miss but what is causing the LV8 to drop?

Another thing...if I park my car on an incline with the passenger side higher than the driver's side, the car will not start. I have to clear flood the car and floor it when starting like an old carb car to get it to start...anyone know why?

TIA,
Kev

 

[John Larkin]

Try leaning the ECM different ways inside the car. Maybe the incline is causing a loose connection. I heard of a car that would cut out when rock music was played. Turned out the kid in the passenger seat was tapping his foot against the ECM and breaking a connection at the ECM with each tap of his foot. Weird, huh?

 

[Nick Micale]

What is your fuel pressure at 25 psi?

Cannot depend on just DS readings at that boost level.

Personally I would not run a 307 pump at that boost, especially with 50#'ers. How old is the pump? I have thrown out more 307's than all others combined. Even 340's get lazy after a couple years.

 

[kevans]

Well...tonight we tried advancing the cam sensor a bit on the ported iron head car and it seemed to clear up a lot...but not all...of the misses. This would coincide with my problem as well since I recently changed the timing set...guess I'll try it tomorrow.

My fuel pressure line off is around 42lbs. I recently checked it at WOT and it built perfectly with boost.

Again...the DS readings spike only 1 frame out of 18.2 frams per second...like the ECM is resetting. Injectors go to about 3%, LV8 goes to about 30, timing advances to about 50 and MAF may or may not drop depending on the run to about 30. I had a similar problem last year and it ended up being the MAF overflowing but an LT1 fixed that problem and allowed me to go to 29lbs without incident.

As far as the 307, it is only a year old and was shimmed by PTE. I was told that it actually outflowed the 340 because of the shimming by a VERY reliable source close to PTE. The ported iron head car is running a 340 that is less than a year old. I also wouldn't think this would cause a single frame error on the computer even if it was running out of gas.

Keep em coming,
Kev

 

[Thunder]

Last year I was experiencing a similar problem. Difference was that all of my ds parameters would drop to 0 for that 1 frame. The car felt as if it had turned off for a split second at wot. Traced this problem for at least a month. Turned out, my ds cable (connector) had slid too far into the ecm. Shimmed it out with some cardboard, and have never seen the problem since.

 

[kevans]

Thunder...we thought about that too but only a few parameters are falling off and never to 0. My car has had DS in for nearly 2 years now without incident but this problem all started after I changed the timing chain. Going to try advancing it some tonight but I have to turn up the boost and it is getting hot out...

Any other ideas?

Kev