Saab Link Forums banner

Car jerks when accelerating and cuts off when full throttle

16K views 24 replies 8 participants last post by  nicat 
#1 ·
I have a problem with 1993 Saab 9000 cse turbo.

I have two problems, and I think the problems might be related.

First, when I give full throttle, the car cuts out.

Second, when driving, when I let of the throttle and then accelerate the car jerks.

The check engine light would flash 5 times, which I found out online it means bad TPS (Throttle Position Sensor). I looked and checked for TPS on the throttle body, and there is none. I have searched this forum and other and found some infos.

So my question is are these problems related, is the bad TPS causing all of this?

In order to change the TPS or fix this issue, do I need to replace the Throttle Body? (New Throttle Body (900$)

Can a Saab mechanic fix this problem for less?

btw..The TCS and ANTI-LOCK lights are on.
 
See less See more
#2 ·
You have a problem with your Traction Control System (TCS).

There is no separate Throttle Position Sensor in your car, it's integrated with the Throttle Body.

Is your car in Limp Home Mode?
 
#3 ·
"When the traction control system on Saabs fail they typically go into limp home mode. Limp home mode causes the car to work only in a dimished power capacity. The name actually says it all. This mode will enable you to get home but that is about all. The car will only run about 30 MPH or so."
Is this what Limp Mode mean? if so, then no. There is no problem with it. Last time I drove 160km/h on highway. So I guess its not in Limp Mode.

I will make a video of the problems tonight and post it on youtube.
 
#5 ·
TCS = traction control system.

TCS is a function of the electronic throttle system. People seem to use TCS interchangeably or as a catch-all for the entire electronic throttle system (ETS).

You might also have an issue with your boost pressure control solenoid/valve. That might be causing the car to over-boost. But my bet is that you will find the main fault to be somewhere within the electronic throttle system.

The electronic throttle body DOES have a throttle position sensor, but it is integral, not able to be replaced on its own.
 
#8 ·
i too have tcs and if i were to guess id say your first problem is the turbo not keeping up with the motor? unless it really cuts out (hard) then you are overboosting like jk says (watch turbo gauge)
...
dosnt hurt to get your codes cleared see if your car runs better.also if you are letting off then getting back on quick thats beating your car hard gotta remember its a heavy car it takes a second to change your momentum
im not defending tcs but holy shit you feel like you have some power when you cross 2 lanes when tcs kicks on
vac TB sucks tho
 
#9 ·
I really wish I can fix this problem. As JK said earlier, it could also be APC valve. I took off the APC valve this morning, and cleaned the holes with Carb Cleaner, then let it dry for 4 hours, and put it back in, its still the same.

It could be APC, because there is too much boost when I accelarate. Maybe someone can tell me how to bypass the APC to test it.

Anyways, I'm going out to record a video of the problem I'm experiencing with this car.
 
#12 ·
FWIW, when we bought my brother's '93 Aero with the same TCS/ETS system as your '93 CSE, it would consistently overshoot boost pressure and hit fuel cut like that, the problem did turn out to be the throttle body itself. We replaced just about every engine sensor, BPC valve, MAP sensor adjusted wastegate, yada yada yada.

Ours did NOT have a fault code stored like yours, it's very possible that is your problem.

Cleaning the BPC valve often won't fix a bad valve, they short out internally, you may want to try substituting another one and see if it does the same thing.
 
#17 ·
A Saab specialist with old enough diagnostic tooling will be the only place that has a prayer of fixing that. I can always get them fixed, but easily half the time the owner decides it's too expensive to justify on a car that old since they can sort of still drive it around.
 
#19 ·
nicat hopefully you are fixed but if not try this. your 9k will be a mirriored image.. meaning your wastegate is sticking out to the right not the left like the picture. anyways grab the pivot point with adjustables or locking pliers.. and free it up. if the rod/ diaphram moves freely in and out( remember its under tension so should be hard to push in, and will automaticaly pop out) if it is free the first time this is not your problem. if it feels stuck wiggle in and out until it frees . dont break anything though.
-cc
 

Attachments

#21 ·
Hey, sorry I could not write back as I was busy with school and work.


I ordered an APC valve, it should arrive by Wednesday and I will try it on ASAP and test it. I think it is APC valve, because it causes bucking as you saw in video and also sometimes there is underboost.

As for the jerk, which I have not recorded a video on it, could be a Clutch issue. I replaced the clutch 6000km ago. I had bought 2 clutch at that time, and the mechanic put the wrong clutch in it.
Because when I release the gas pedal and then accelarate the car jerks. BUT WHEN, I press the clutch pedal little bit and then give gas it doesnt jerk.

So it could be the clutch or something else. I'm not sure.

The clutch he put in is the same size (inner and outer), but the clutch he put in has a different shape inner diameter and its in silver color. Check out the attachment and let me know what you think.
 

Attachments

#22 ·
I got the APC valve and I tried it right away. The problem is gone but there is very little boost. The "bad" valve used to give me extreme boost (orange) and it would do bucking.

But the new one is OK, but there is very little boost.. the boost is in the middle (yellow?)

Do i need adjust the pressure somehow?
 
#23 ·
I got the APC valve and I tried it right away. The problem is gone but there is very little boost. The "bad" valve used to give me extreme boost (orange) and it would do bucking.

But the new one is OK, but there is very little boost.. the boost is in the middle (yellow?)

Do i need adjust the pressure somehow?
First make sure you don't have a leak somewhere, like a loose hose, or one with a hole. Then from there, you can adjust the base boost via the rod on the WG actuator. The more you tighten it, the further in it goes, thereby increasing base boost. However, don't crank it in too far. A turn or two and test it. Having a real boost gauge helps to know where you're at, since the factory one is mostly useless.
 
#25 ·
Hey Im back with good news!

So 2 days ago I went to Aktive Motors in Oakville, Ontario. I had chance to meet the owner Christian (a very good guy!)
I had the following problems b4 i went there. TCS CTRL + ANTI LOCK, and SRS light was on.

The SRS light was resetted and light never came back.
The TCS + antilock light was a bad MAIN RELAY( its under the hood). I changed the relay and the lights disappeared.

He also told me that the Jerk on the car might be the vacuum hoses. So today I changed 98% of the hoses and the "jerking" problem almost went away. I think the problem might be lower engine mounts. I will go back to Christian to get them changed b4 January.

I also cleaned the Throttle Body, now it Idles a lil better.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top