as per scanner MAP makes SES light on and off at idle and giving knock
what is the problem????
my set up is:

1- 388 CI stroker with compression ratio 12:5:1 ,rod length 6 inch and milling heavy duty oil pump.

2- LE cam 245"/253" , 612"in/612"ex LSA 107

3-Trick flow 7.10" push rods.

4- M6.

5- 42 LPH fuel injectors.

6- 4.10.

7- LT4 cylinder heads 2.02 intake and 1.60 exhaust with Patriot valve springs.

8- porting the intake to 58mm with throttle body.

9- headers 1 3/4 with cat back borla.

10- ram air.

11- EGR,AC,Air deleted.

12- Cloyes double chain roller.

13- Walbro 255LPH.

14- LT4 knock module.

15- electric water pump.

16- under drive pulley.

17- AC deleted kit.

18- LTCC coil conversion to 8 coils.

19- Stage 3 clutch.

 

Oh boy...what are you doing for a tune? Which code specifically are you getting? Is this an OBDI or OBDII car (you list things like underdrive pulley, but not what year vehicle??).

 

sorry for that lol.. it is 95 OBDI

 

There are two different codes for a faulty MAP sensor. Which one do you have? With that cam, I'm going to guess you get a code for "high MAP" (= low vacuum). That's a huge cam, and its not going to pull enough vacuum to satisfy the PCM diagnostic for MAP at idle (above 65kPa sets the code).

How did you determine "MAP makes SES light on and off at idle and giving knock"? Sounds like two different problems. What grade fuel are you running? Have you checked dynamic compression ratio (DCR) to insure it is withing the limits for the fuel you are using?

Who tuned it?

 

as per scanner the code says 1)the MAP sensor sometimes working and sometimes not, the car run rough especially at ideal i mean lower than 1500rpm if the RPM is less than 1500 the SES light on,and when i accelerate to 2000 RPM the SES light goes, 2) O2 sensor are not working

 

In my 16 years of working on these cars, I have never seen a code that says "the MAP sensor sometimes working and sometimes not"....... what was the SPECIFIC NUMERICAL CODE?

Lacking much punctuation, I'm going to try and break down what you wrote into logical pieces:

We'll assume that you mean "idle". A cam that big is going to be hard to tune for a "smooth" idle. I'll try this question again - who tuned it?.... and add - was it a mail order tune or a dyno tune?

We'' assume you meant to type "when I accelerate to 2,000 RPM the SES light goes out". That would make complete sense. When the engine is at low RPM, then PCM is looking for a MAP level of 65kPa or less. It isn't seeing it because of the big cam. It turns on the SES light. As RPM goes up, the PCM is no longer looking for a specific MAP kPa reading.

Again, confusing. In your original post, you indicated the code was for the MAP sensor, and you were getting knock. Now you are indicating the O2 sensors are not working. How do you know they are not working? Do you also have a code for the O2 sensors? Its going to be very hard to tune that thing at idle, with the O2 sensors in closed loop. The high overlap is pissing raw air into the exhaust, and the O2 sensors will cause the PCM to pour in fuel, making it run pig rich, and run even rougher.

Again.... WHO TUNED IT?

If you don't answer the questions, it makes it very hard to help you.

 

thank,it is mail order tune

 

Is it really so hard to answer all of Fred's questions? Are you even reading? Or more important, comprehending?