J-Body Automobiles Forum banner
1 - 16 of 16 Posts

·
Premium Member
Joined
·
17,284 Posts
Discussion Starter · #1 ·
So on the way home from the bash, Jenna's car suddenly developed the following problem. She has a 1994 Beretta with the 3100 and the 4 speed auto with 78K miles.

The engine is sluggish and it will buck under cruising speeds above 50 mph. The engine runs rough and it feels and sounds like it is only running on 4 or 5 cylinders.

So today I tore into it. I changed the ICM and coils, aswell as the spark plugs and the wires. I now have strong spark on all 6 plugs. I changed the O2 sensor. I pulled out the fuel rail and slipped a piece of cardboard underneath it and cranked the engine. All 6 injectors are firing with a good spray pattern and yet the problem still persists.

On a side note: for the past few years, the diagnostic port on the car has not worked, so I cant ground the test terminal to get codes for some reason. A new ECM is the next thing on my list.

Any ideas??

Thanks,
Brad
 

·
Registered
Joined
·
931 Posts
You can't ground the diag port to get codes. You must use a scanner. 1994-95 SFI motors are OBD1.5 weirdo crap.

Is the crank shaft position sensor about to take a crap?? The 7x one in the block.

That motor doesn't have many miles on it (mine has 200k lol) so I'm not sure if it could be mechanical. If the CPS 7x sensor doesn't do it then I would get a compression test if you can.

Maybe the MAP is whacky? Eh not so sure on it but if you have a spare to try might as well.

If getting electronic parts stay away from Autozone their stuff is crap. Dies in less than a year.

Does the motor still run rough while idling in park/neutral?
 

·
Premium Member
Joined
·
17,284 Posts
Discussion Starter · #6 ·
How many pins does the OBD 1.5 port have? Jenna's has the OBD 1 connector.

Well, I guess I will nurse it over to the parts store to get it scanned tomorrow.

I will throw on my spare MAP sensor tomorrow and see if that helps.

The fuel pressure looked nice and steady and at the correct pressure when I tested it today and the fuel filter was changed about 4 months ago, so I dont think that would be an issue.

Thanks for the help so far.... I'll keep you updated.

Brad
 

·
Registered
Joined
·
1,885 Posts
Brad91Z said:
How many pins does the OBD 1.5 port have? Jenna's has the OBD 1 connector.

Well, I guess I will nurse it over to the parts store to get it scanned tomorrow.

I will throw on my spare MAP sensor tomorrow and see if that helps.

The fuel pressure looked nice and steady and at the correct pressure when I tested it today and the fuel filter was changed about 4 months ago, so I dont think that would be an issue.

Thanks for the help so far.... I'll keep you updated.

Brad
did you observe the fp while driving or at idle?
 

·
Registered
Joined
·
931 Posts
It is a OBD1 connector. It's just a flash style ECU and no one supports it for after market tuning. If going to a parts store, they may have a cheap scanner, and if that's the case they will probably only be able to pull a code if there is a check engine light currently on.

I've used a $$$ snap-on scanner on mine and it could read history stuff and reset codes/etc.

Try the MAP and if that doesn't work it could be the 7x sensor about to crap out. Mine was a bit flaky and missing out and back firing before it died. Then I got an autozone one and it just plain quit when hot in less than a year which made me buy a new ICM until I figured out it was the sensor again.. grrr
 

·
Premium Member
Joined
·
17,284 Posts
Discussion Starter · #11 ·
MAP didnt help, and the cps has a resistance of 980 ohms, right in the 900-1200 that I think it should have..... so I am at a loss.....

Anyone know the specs to test the camshaft position sensor???

Brad
 

·
Registered
Joined
·
931 Posts
Yes test the TPS. The CPS will look ok until it gets hot then it can start acting funny.

If the camshaft sensor goes out then it will revert to batch fire. You could try unplugging it and see if the car runs better, to rule out a whacky signal.
 

·
Premium Member
Joined
·
17,284 Posts
Discussion Starter · #14 ·
Tested the TPS and it was fine..... ran out of time and options, so I took it to a friends shop to diagnose... hopefully they will find the issue quickly.

I'll let you know what they find.

Brad
 
1 - 16 of 16 Posts
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