I just finished up the cam install in my 04 GTO. At first, the car would not idle and I had to keep my foot on the gas to keep it running. I reset the TPS and IAC and it seems to idle just fine now. I thought I would try to drive it to make sure everything is working right. The car has no throttle response, bogs down when trying to accelerate and will not even accelerate. Then it wouldn't idle anymore. The car is not tuned yet, but will be getting tuned sometime this week.

Everything was installed correctly, the cam was installed straight up, I triple checked the pushrod length on both banks. There are no misfires. I don't think there are any vacuum leaks but I will be double checking for that tomorrow. It has all new gaskets everywhere.

The only codes it has are P0101, for the MAF and P0106, for the MAP. I've heard these codes are common after a cam swap, but I'm thinking there are other issues due to the driveability problems. Could these issues be due to it being untuned? I'm only confused because I'm seen several people drive cam only cars while untuned.

 

I've done fbodys and vettes mainly but I've never seen a map or maf code after a cam swap. Just p0300 multiple misfire. I've drove 5 hours one way untuned and never had a problem other than stopping quick the car would die. That was with a 232/234 in a ls1.

 

I had that issue before. One of the wires for the MAP was pulled out of the connector. An 11 dollar new pigtail solved the issue.

 

ya there shouldnt be a map code and most likely not a maf one either. sometimes the map sensor prongs get bent when trying t plug the connector in since you're doing it blind. also make sure the bellow are the maf is tight and you have no vac leaks after the maf

 

Well the car definitely has a vacuum leak. The vacuum gauge was reading between 4 to 7 in Hg at idle. What I will be checking later:

Pull the intake off to make sure all of the gaskets are seated properly. Then torque the intake to the proper specs of 89 in lbs in two steps, and in the proper sequence.

Check for leaks around the throttle body and all pcv lines. I replaced all of those hoses, so I'm pretty sure the problem isn't there.

Check the back of the intake around the MAP sensor and brake booster hose for leaks.

And lastly double check the pushrod length. I really doubt they are too long, but if they are they could be causing the valves to hang open. I'm sure it would be easier to do a compression check for this instead of pulling the valve cover, right?

Any other suggestions or comments?

 

What are the cam specs? Is this a A4 or M6 car?

 

M6 car with ms3 cam stock 241 heads and ls6 intake.

 

I just pulled a spark plug and it is running extremely rich. Could the rich condition be caused by running open headers? It just doesn't make sense for it to run so rich with such low vacuum...
Compression looks fine. Was between 150 to 180.

 

Open hearers? Any more little details you want to mention?

You can't run open headers in closed loop with O2 sensor feedback.

And a MS3 cam will cause P0101 and P0106 codes on a stock 04 GTO OS/calibration. Nothing wrong with the sensors. It is the diagnostic limits.

 

My 02 threw a MAP code only after the cam install. I can see how it would with the difference in air volume coming into the motor. I would get it tuned. My 96 TA threw a MAF code once, all of the wires at the MAF looked great. I dont know how a gto is routed, but on a fbody there is a harness that runs between the passenger side header and ac/heat box in the engine bay. There is MAF wires in that harness, and mine had burned through
on the header.

 

There's an older thread I made a few years ago about me having absolute FITS trying to figure out what was wrong with my car... Identical symptoms.

This was just after a Fast 78 (or 92, can't remember) install on a full bolt on Camaro.

Unplugging the MAF made the car run a lot better, so I thought MAF. Bought a low mileage (30k) MAF on here and threw it on, symptoms came right back.

Someone finally mentioned pulling the intake again and looking at the wires that go into the MAP pigtail. Lo and behold, I think a brown or a green one had actually pulled out.

New pigtail soldered in and the car ran like a champ after that.

Not sure if that's YOUR problem, but I'm just sharing my experience.

I was about 2 cups of coffee and an argument with the wife away from burning the car to the ground... I was that aggravated with it.

 

MS3 with open headers and no tune...enough said.

 

Here it is. It's a P0107, but could be related...

https://ls1tech.com/forums/generatio...-me-p0107.html

 

I installed the rest of the exhaust and re checked the pushrod length, it's good. I cleared the codes and the car idles now with no check engine light. The car is still running very rich. The vacuum gauge still reads 7 inches but when I rev it it goes up to 15 to 20. That's strange because when the throttle opens the vacuum should drop. I don't understand what's going on here, and Dr Whigham I'd be lying if I said I wasn't frustrated with this issue. Everything seems to be okay I don't understand why it won't run right. All the wires to the MAP and MAP are good.

There are no vacuum leaks. I have spent hours checking for one and there just aren't any. The only thing I can think of now is that I installed the cam 180 degrees out. I've heard that the crank sprocket has two dots on it and I may have been looking at the wrong one. What do you guys think? I'm about to give up and take it to my tuner to see what he thinks.

Edit* That can't be right. I am 100% sure that the number one piston was at TDC and the cam pin was at the 3 o'clock position. Also, now that the car is warm, if I try to start it, it will not idle. Still no codes.

 

Not idling on a hot start is pretty normal, as are the fouled plugs without a tune. I ran my car for around 300 miles without a tune and coming to a stoplight was like river dance trying to keep it running once it was hot.

I think a tune is going to take care of things at this point.

 

Dr whigham I think you're right. I've done some searching and it seems that a cam this big is supposed to pull only 7 in Hg at idle. I honestly can't think of any mechanical reason that could cause the car to run like this so it must be all in the tune (and my head). I will call my tuner today and see what he thinks.

 

It makes sense. There's a lot of parameters the PCM is looking for that well... Aren't there anymore. I think (hope) a good tune will get you all sorted out!

 

Well me and some friends towed my car to the local tuner yesterday and I just picked the car up a few hours ago. As it turns out, there was some issue with the pushrods being way too short. I measured for 7.35 to get to zero lash, then added .05 for preload. I thought the stock ones would work just to get it running and tuned until I got the aftermarket ones. I took the car to a local tuner who is very well know for his work with LS engines. He discovered I had pinched a knock sensor harness under the intake at the very back. He also changed the pushrods out to Comp 7.4 and tuned the car. It runs fantastic now! It barely even surges below 1500 rpm and gets 25 mpg on the highway! It totally surprised me how well the car drives with a cam this big. I am really happy with my car now!

 

Good to hear it's all back together. How did you originally measure the pushrods?

I'm about to do the work myself in a couple of weeks or so. I'm considering just replacing the knock sensors while they're all exposed (I had a knock sensor error code after switching to long tubes, and replacing the motor mounts).

And what'd you do? run through two tanks of gas in one day?!