motor bogs when full throttle

[ez944]

The car runs fine idles rough sometimes when cold, when I hold the throttle wide open the motor will bog with no power at all. it will redline without going full throttle.

[dogslovetrucks]

Turbo or N/A?

[ez944]

NA

[97XRAY]

I'll bump this back to the top;
I too have experienced something like this. it only happens in my NA when I've just started it and drive relatively hard shortly thereafter - eg. I pull out of my driveway into on-coming traffic and need to gun it to avoid an accident (hey, I know it's stupid - at 7am, I'm stupid!)
Maybe some of you guys who know more about the actual design of the pistons / valves might shed some light for us.

[Bob's944]

Are you hearing any strange noises around the timing belt cover?? This sounds similar to what was happening to my car when the waterpump was going. What happened was water and steam was escaping thru the front of the waterpump, since the waterpump is under the timing belt cover and the distrubutor cap is at the top of the cover, steam was causing the spark to fail and the car bogged down seriously under full throttle. It would run better at lower rpm's. It didn't take long after those symptoms till the temp gauge started to climb into the red and a full failure of the pump to finally happen.

[hoff944]

97XRAY: I had a problem similar to yours and ran some Chevron Techron fuel system cleaner through my 944 and she ran fine on cold start up after that. You might try that.

[turtle944]

I have had the same problem here on occasion. It almost feels as if I wasn't playing off the clutch enough. You put it in first, play off into gear, which works fine, and then gun it at which time it bogs down. Generally if I leave the car sit for a few seconds and warm up, it doesn't happen.

I have run techron through the system, and it seems better then, but a week later, it returns.

Brian

[Scott R]

Could be blockage in the catalytic convertor.

[todwic]

fuel pressure regulator? iceburgs in your fuel rail?

[88_944]

Maybe bad air flow sensor.

[97XRAY]

This seems like a good time to mention a weird thing. My car, as it says in my signature, is a Euro. I guess when it came state-side the DOT said it needed a Cat - so somebody just welded one on. There's no bolt on area from except where the exhaust manifolds meet the block!

Thus far I've assumed it was no big deal and I'd have my mechanic weld me a new bolt on area some day when I felt like spending the money and getting a high flow cat-back.

What do you guys think? Could this be the culptrit of the engine bogging?

[mike944]

I have a simmilar problem with my '84. I have always assumed it was the TPS (throttle position sensor). On mine, if i floor it, it accellerates pretty well, but at higher RPM's if i back off the throttle maybe 10% from max (90% throttle) i get a noticable increase in accelleration. BUT... if i push the pedal down to 90% to start with, then i floor it, i don't notice
any decrease in accelleration, but if i back it off to 80% i notice an increase.

One of these days, i'll get around to replacing the TPS.

anyone else notice this?

Mike

[ez944]

Yes my mechanic says thats what it probably is( TPS ) he said moisture gets in the throttle body and corrodes the TPS switch. I stored the car over the winter and the throttle was sticking wide open from the body so it makes sense. Thanks. I will take it apart and try to clean it after I am done fixing all my oil leaks.

[ez944]

fixed that problem by cleaning out the throttle position censor. but now it bucks and bogs at 2000-3500 rpm's started very light only on the highway now its so bad I can't drive it. It chugs at 20mph on up. idles perfect starts great and revs fine but runs ruff at steady rpms.

[ez944]

No but I have only had the car for about 60,000 miles and I would think it wold run bad all threw the rev range then. I'm thinking its the fuel presure regulator. has any one had this problem.

[SoCal Driver]

Originally posted by ez944
No but I have only had the car for about 60,000 miles...

Replace the fuel and air filters.

Run some injector cleaner through it.

[justin]

I second what So-Cal says.

[ez944]

Just did all that no change.

[SoCal Driver]

Originally posted by ez944
Just did all that no change.

Good. That's off the punch list.

The redline without going full throttle is not redlining. You are getting most likely a restriction in the flow of fuel.

You have cleaned and adjusted the TPS. Both switches; the closed one and the full throttle one. Both are closing/opening as intended.

I would have to eliminate the water pump leaking as your car is not at operating temp when you pull out of your driveway to go to work.

I would have to look closely at the CAT. Though this may not be the problem. A more recent exhaust system should bolt up to your car. You might want to see if you can find one.

Here's what the DME supplement lists as potential problems:

Engine Cutting Out:

Ground Connections
Fuel Pump Power (Relay)

[u]Poor Acceleration:[u/]

Ignition System
Air Flow Sensor
Throttle Switch
CO and Idle Settings
Intake System Leakage
Alternator/Regulator (low system voltage)
High Altitude Switch

Both Cutting Out and Poor Acceleration have double hits on:

Ignition System
Air Flow Sensor
Intake Leakage
Alternator/Regulator


As the last item you worked on was the TPS I would look at that again.

Read another thread about intake leaks and these are not confined to the larger tubing for the intake. Could be vacuum tubing too.

Keep us posted.

[ez944]

The problem was the cap and rotor. for some reason the rotor was hitting the cap and did allot of damage, hard to believe the car ran at all.
Thanks for the replies.
now to get a replacement.