black944 turbo

Do you have a fuel pressure gauge? Have you boost leak tested the system yet?

TheDice951

i did check the plugs more than once and all look great....

replacing the couplers is next on the list....

i read boost from the intake manifold, when im getting on it it reads full boost at the manifold even when it "hits the wall" so im thinking its not a boost leak....

i have noticed that it feels a bit different with normal driving as well... yesterday i was driving to work and it would stumble a bit on accelaration but for a split second and thats it... its not a smooth clime through the rpms... ^^^this is under NORMAL driving^^^

TheDice951

would an O2 sensor make my car do this? I read about it on the Clarks garage tech stuff and it seems like it could.

I disconnected it and drove to Wal-Mart to grab some stuff, thinking that driving it in open loop would make it run off the maps eliminating the issues I’m having. it did not change the way it drove too much... it drove a bit smoother until I hit boost but then it would hit a wall and not accelerate just like before. so I’m thinking that the o2 is screwed and the computer limits the boost and such for the cars protection????

how wrong am I?

Mighty Shilling

O2 sensor shouldn't do that, because when you go to WOT, it should go to the WOT map, instead of operate in closed loop. the O2 sensor is there for closed loop operation.

That being said, it may not be a bad idea to replace the O2 sensor. Porsche states it has a life of approx 60,000 miles, and if you can crimp wires, you'll be able to replace it with a generic bosch sensor for $40.00. part numbers are on Clark's Garage.

fast951

A few questions to help us narrow it down.

Can you hone in on the problem and see if it's "boost" related or "throttle position" related or "RPM" related?

- You mentioned, it runs fine if you gently apply throttle. Are you building boost? If so, how much?
You can build lots of boost in higher gears at PT; you can left foot brake to create load without exceeding speed limits..

- What happens if you go WOT at lower revs, before it builds boost? If it works, eliminate the TPS.

- Can you check the MAF voltage on DME #7? What does it do when you hit the wall?

- Are you seeing black smoke out of the tailpipe once you hit the wall?

Obviously something got damaged/disconnected causing the problem. It's a matter of finding it, hang in there.

TheDice951

fast951, last night i was messing around with it to try and answer your questions...

it does build boost, i have it at 12lbs, but, when i gradually apply the throttle it only hits 8lbs even at WOT. when i "slam" the gas it hits 12lbs and does the hesitation. it kind of feels like it doesn't know what to do, it catches and then lets go if you know what I'm saying. on and off kind of thing.

if you put the peddle down at low rpms it starts to accelerate and then seems like its surprised when boost comes on and then says "oh **** here it is" and it just comes on after boost started to build and then starts popping.

i have been seeing black smoke since i bought the car. the turbo seals are leaking, i just haven't been able to replace it yet.

i am not 100% on it but i think its boost related. but the reason im not sure is sometimes before boost, when im just driving, ussually from a stop sign in 1st, the car kind of hesitates an "catches" and goes.... but thats not all the time....

its not that it "runs fine" under gental throttle, its just not as bad...

TheDice951

ok, i replaced the O2 sensor last night and found that the vacuum line for the computer wasnt hooked up. so i hooked it up.

no change on anything?

i did however notice that anytime i get in it at all there is a STRONG fuel smell... i figure its because its not burning the fuel fast enough? so that would be a fuel or ignition issue?

i have a new cap and rotor, sparkplugs are good, wires are only a year old and the fuel pressure is around 35 and the fuel filter is new.....

TheDice951

just checked for boost leaks AGAIN and put like 30psi on that shizznit and got NO leaks

replaced:
fuel filter
distributor rotor (cracked)
TPS sensor

checked:
spark plugs
wires
compression
boost leaks
fuel pressure
vacuum leaks
turbo
exhaust


i dont know what else to do!!! what the hell is wrong with my car?!?!?!

Dougs951

I will give you $8 and a pack of gum.

But really it has to be something. Could the cam be off a tooth?

carlege

Check your chips and see if they are seated all the way.

TheDice951

I checked timing, and replaced the u2 sensor as well...

It seems to be running really rich and now stumbles on acceleration all the time not just in boost...

I will look at the chips tomorrow... That would make sense also....

TurboTommy

I still don't think you ruled out the injectors.
Spark plugs could still look fine even with an intermintent fuel delivery problem.

TheDice951

Well, since my car kills me with fumes every time I drive it, I am thinking it's getting plenty of fuel... The all click normal and have been cleaned as well.. So, I am pretty certain its not a fuel delivery problem..... But who knows....

TheDice951

Does anyone have any other ideas??? I hit a wall!!

What next?

jasonlp

film it and post it