Help! Houston we have a problem!

[jamison]

I have a 90 coupe with a 4 speed automatic. when it is at about 180 degrees or under the car runs fine, i can hit on it and it just accelerates up to speed with no problems. However when it gets up to 210 degrees and above it becomes very hesitant when i give it some gas. I can put my foot to the floor and it seems like i am only resting my foot on the pedal, but after a couple of seconds the SES light comes on and then the car takes off like it should at full open throttle. Along with this hesitating take off there is this loud rattle noise coming from under the car near the engine that does not happen when the car is under 180 degrees. As of right now i have not been able to look into the problem but i think it could possibly be the Throttle Positioning Sensor (TPS), Manifold Air Temperature (MAT) sensor, Coolant Temperature Sensor, or something from the fuel system. As far as the rattle possibly the exhuast or emissions. PLEASE HELP!

 

[gmjunkie]

I believe I'd have the catalytic converters checked for possible restrictions!!

 

[LT4man]

Since the Service Engine Soon light is illuminating, I would check for codes immediately. Then report your findings here.

AFTER CHECKING FOR ENGINE CODES, PLEASE SAVE THE !

 

[jamison]

The codes where 32-EGR and 43-ESC. I know why the knock sensor is showing up, the connector broke and i had to get a new on. But no clue with waht to do to start seeing what is wrong with the EGR.

 

[vetteoz]

I know why the knock sensor is showing up, the connector broke and i had to get a new on.

ECM has to see the knock sensor present
The noise you are hearing is probally engine knock from having no spark retard under load
Can get new connector here
http://www.eficonnection.com/eficonnection/tpi_pigtails.aspx

 

[KANE]

The codes where 32-EGR and 43-ESC. I know why the knock sensor is showing up, the connector broke and i had to get a new on. But no clue with waht to do to start seeing what is wrong with the EGR.

A malfunction in the EGR system can create popping noises. I'd be incline to say that your EGR valve may be worn out. If it is the original EGR valve... odds are pretty good it should be replaced. You may have carbon deposits that are keeping it open- or it could be so far worn that it is opening and closing based upon the pressure of the EGR air stream and not from the vacuum controlled by the ECM.

As for the ESC, it is more likely your ECM has placed itself into limp home mode as a precaution. During the limp home mode, the ECM retards the spark back as far is it can go. You won't develop full power and it will run as if it were lazy. You need to get the knock sensor hooked up soon.

 

[crash]

ok. years ago when the 3c systems came into play we were told at the training schools to start with the highest code first. your highest code as you stated is 43. that is the electronic spark control system. you stated that knock sensor connector was bad. repair the connector-clear all codes and redrive and see how it goes. if codes are reset refer to a fsm and start folling the flow charts for said codes.
the knock sensor signals the esc that there is a knock in the motor so the esc kicks the timing back.
good luck rich

 

[jamison]

Thanks everyone for all the help. I fixed the knock sensor connector and i have not had that code show up again. But the EGR code 32 still keeps appearing along with that rattle only during 3000 rpm and at 200 degrees and above. so i don't know if the EGR valve is bad or if at higher rpm and temperature i am having vacuum issues.

Also at full throttle it does not have any hesitating just that annoying rattle.

 

[crash]

Thanks everyone for all the help. I fixed the knock sensor connector and i have not had that code show up again. But the EGR code 32 still keeps appearing along with that rattle only during 3000 rpm and at 200 degrees and above. so i don't know if the EGR valve is bad or if at higher rpm and temperature i am having vacuum issues.

Also at full throttle it does not have any hesitating just that annoying rattle.

im not sure but i think you have a heat tube coming off the right exhaust manifold. if so it has a sensor in it for the egr systen. i had a 89 and it kept setting that code. i got out my fsm and read the flow chart for that code. all indications pointed to that sensor.
i bought one and put it in. problem solved no more code.

 

[Hib Halverson]

Engines with EGR will knock if EGR is not working.

Engines tend to knock more when coolant temperature is higher.

Use the Factory Service manual diagnosic info for DTC32 and repair your EGR system. My guess is, once you do that, the knock will stop.

 

[gw962]

The '90 does not have a temp sensor in the EGR tube.

If the diagnostics lead you to replacing the EGR valve, make sure it is a Positive pressure unit. (There will be a P at the end of the part numbering).

 

[vetteboy86]

ECM has to see the knock sensor present
The noise you are hearing is probally engine knock from having no spark retard under load
Can get new connector here
EFI Connection

I have an 86, and I was doing some troubleshooting trying to determine if I had a bug in the code, if I was getting false knock. So I ran the car for one scan with the knock sensor unplugged. I didn't get any codes. I realize mine is an 86 and the vehicle in question is a 90, so I am making no claims to that, just what I expereinced.

I don't think you are implying this, but I just want to be clear. I don't personally believe it is a good idea to rely on the knock sensor to retard timing for drive ability. You want the tune to be a few degrees less across the load range than the point where knock occurs.

 

[Schrade]

I have a 90 coupe with a 4 speed automatic. when it is at about 180 degrees or under the car runs fine, i can hit on it and it just accelerates up to speed with no problems. However when it gets up to 210 degrees and above it becomes very hesitant when i give it some gas. I can put my foot to the floor and it seems like i am only resting my foot on the pedal, but after a couple of seconds the SES light comes on and then the car takes off like it should at full open throttle. Along with this hesitating take off there is this loud rattle noise coming from under the car near the engine that does not happen when the car is under 180 degrees. As of right now i have not been able to look into the problem but i think it could possibly be the Throttle Positioning Sensor (TPS), Manifold Air Temperature (MAT) sensor, Coolant Temperature Sensor, or something from the fuel system. As far as the rattle possibly the exhuast or emissions. PLEASE HELP!

Every car runs perfect in open loop (cold), and runs perfect with the hammer down. Means not a thing in the world... People get ripped off by mechanics, leave the shop in open loop, problem solved. Joy? Nope. Car goes closed loop, trips fault, back to the crook for another fishing expedition, and the process repeats, while your cash goes away yup!!!

Fix the KS. Timing will stay retarded until fixed.

32 can be more difficult. A vacuum leak can cause this. Does your lope idle when warm?

 

[jamison]

ok first off i fixed the knock sensor. second i completely agree about crook mechanics, thats why i do everything my self. no one puts a finger on my car unless its me or my dad.

 

[KANE]

...second i completely agree about crook mechanics, thats why i do everything my self. no one puts a finger on my car unless its me or my dad.

I know how you feel. I only outsource when absolutely necessary. I've never added up the money I've saved over the years but I'm sure it is substantial.