Falling on its face

[Rusman]

My car has been intermittently falling on its face above 4k. I usually notice this is first and second only. I can't recall if it's happened in third, but I know not in 4th, and definitely not 5th :).

My friend thought it might be weak/dead valve springs. Very good suggestion, I thought, as I've been told that the stock 94/5 Cobra springs are crappy and will pretty much be useless the first time the engine is revved past 6K (I've done it a few times...oops). It seems to happen only when the revs come fast, like in first or second. And when it does fall like that, if I hold it floored, it seems to just stay there and not want to pull any higher at all.

Does that sound like a possibility? How can I check the springs? If it isn't the springs, what else could it be?

[Rusman]

/me hopes someone has an answer

[Rusman]

Well, this problem is still continuing, but today it happened again and was the worst ever. When I punched it and got to the magical ~4K mark, the car fell completely flat on it's face (the front end actually settled down to normal position) and it felt like the rpm's stopped climbing where it was. Keep in mind this is happening with the pedal to the floor.

My car is fucked.

[red95gts]

How old is the fuel filter? What's the fuel pressure at?

[Rusman]

Dunno what the pressure is, but when i put the AFPR on a couple years ago, it was set to stock levels (39psi?) with vacuum...I think. I can check it again tonight.

Fuel filter is about a year old.

[Neighbors]

Could the coil be giving you fits? Does it act like it's loading up? How old are your O2 sensors?

...thinking out loud...

[Rusman]

Coil is aftermarket...about 2 years old Crane PS91.

Doesn't feel like it's loading up...it just kinda dies...like if I went from floored to completely off the gas (without the engine drag) in a split second, though the pedal stayed floored.

What else?
I did a full tune up no more than a year ago which included cap, rotor, plugs, wires (Accel 300+), and fuel filter.
Fuel pump is also around 2 years old and is a walbro 255lph. Pressure was set to factory and hasn't been checked since.

I have a Prom77 Mass air, which could use a cleaning :).

O2's are also about 2 year old Bosch replacements.

I am not getting any check engine lights and the car seems to run fine but for this problem. I haven't tried to pull any codes yet, though. I'll do that when I check for the FP tomorrow since I didn't get around to it tonight.

[Shaggy]

How many miles on the timing chain?

[Rusman]

Stock, so it's ~85K.

Though I've been told that the timing chain normally doesn't need to be replaced.

[WA2FST4U]

Have you tried resetting the computer?

[Rusman]

Nope, but I will try that!

[Rusman]

Got an update on the situation for you. Today on the way to and from work, I could pretty much duplicate the problem whenever I wanted too. I also tried it in second gear (when second gear would actually engage) and usually got the same problems.

When the problem did happen, I decided to hold it a little longer than I ususally do to see what it would do. It would either STOP climbing in the RPMs period, or it would very, very slowly climb, and feel like it was struggling the whole way. It also felt like it was sortof jerking or lurching somewhat. Keep in mind my foot is planted on the floorboard during all of these tests.

I got home and decided to go ahead and check the codes. I got code #212 on KOEO test. 212 is "Loss of IDM (Ignition Diagnostic Monitor) signal - short to ground in SPark OUTput (SPOUT) circuit".

This is a very familiar code to me, but the symptoms aren't. I've experienced two failed stators and both times this was the code I received throughout the whole ordeal. At first, the car would intermittently stall and restart (while driving) until it progressed to completely dieing and stranding me. Both times I replaced the distributor and was ok for about a year when it started failing again during the hot summer months.

After I ran the test tonight, I cleared the code and took it for a test drive. I couldn't duplicate the problem in the severity that I had experienced before. I was able to feel some kind of missing or stumble in the higher RPMs, but it always ran up to 5500/6000 without a problem. I did notice that although it ran up all the way each time, a couple of the runs did feel lower on power in the upper RPMs, but that could be my imagination.

When I got back, I ran the KOEO again and the code had returned. I would also like to test just driving around keeping the R's low and see if the code returns.

So, my current plan is to continue to monitor the problem and search for another distributor to test with. If someone has one, I'd really appreciate it :D. If that cures the problem, I'll just buy a new one and be done with it!

If you read all of that, thank you! :)

[Saleen91]

I see you have a Crane PS91 coil. I had the exact same problem with this coil. After pulling it out of the bracket that holds it I could see the plates were seperating and could actually wedge a thumbnail in between them. I replaced it with an ACCEL coil and instantly my dyno show a 10rwhp gain across the board and the cutting out at high RPM stopped.

Do you still have your stock coil sitting around? If so, swap it out and see how that does.

[Rusman]

Yes I do, Ben. I originally swapped it out the first time I had this problem. I'll swap in the stock coil and see what happens.