help with studdering

**TedsB4Csled** · 11-25-2009, 01:15 PM

PCV line replaced less than a year ago by dealership. Has some oil on PCV valve so I tried a new one the other day.

AIR deleted and blocked off on exhaust manifold.

It sure does feel like it is a vacuum leak though.

Recent plug wires, plugs etc...

Recent o2s.

Replaced all 8 fuel injectors and fuel pump.

Replaced muffler with hooker muffler.

Shorty headers/ceramic coated off E-bay

Nick Williams checked my tune and said it looked good, but it does backfire. We could not get it to studder that day

Compression check was great on all 8 cylinders.

TPS replaced.

SLP MAF, lid and bellows.

Studdering is very random. It happens when I get under load at a fast rate. If I drive like a grandmother it seems fine. At least a slow grandma. lol.

*** $100 anyone? Seriously! ***

?

**TedsB4Csled** · 11-25-2009, 01:21 PM

Originally Posted by RealLiveMD

After months, and hundreds of dollars at different shops, I found a vacuum leak. There was a vacuum hose that ran pass my battery to the ac/heater vac tank. The acid corroded the hose. Problem fixed. The beast is back.

Still not sure if this may be the culprit. Where is it? What does it do?

**Frost** · 11-25-2009, 01:28 PM

Don't you live near Richmond?

**TedsB4Csled** · 11-25-2009, 03:46 PM

Asheville, NC. About 6 hrs from Richmond.

**Frost** · 11-25-2009, 05:58 PM

thought you were down near Colonial Heights for some reason... oh well.

**TedsB4Csled** · 11-26-2009, 02:30 AM

Originally Posted by Frost

thought you were down near Colonial Heights for some reason... oh well.

No, Asheville. I remember buying these injectors from you. Work great. Wish I was closer.

**TedsB4Csled** · 11-26-2009, 11:34 AM

Ok someone is advising me to replace the crank position sensor, clean the MAF, double check my fuel pressure & filter. Let's see if he gets the green!

**RealLiveMD** · 11-27-2009, 01:59 AM

Originally Posted by TedsB4Csled

Still not sure if this may be the culprit. Where is it? What does it do?

I had two vacuum leaks. Coming from the back of the intake manifold, there is a MAP sensor. In that area there is one hose that use to hook to your AIR. Make sure that it is capped off. The second hose snakes fromt he back of the manifold over to the passenger fender well. It then becomes bundled in a wiring harness. The harness snakes into a hole that is between the battery compartment and the front bumper. The hose then snakes under the batterry tray into a round plastic about 8 inch container. My hose was corroded at the level of the battery tray. When the engine moved certain ways like WOT it would torque and seal the leak. Then while driving normally it would studder. I feel your pain. The container is only about 10 bucks at napa.

If this doesn't work. swap maf's with one of your buddies for a week. I have a brand new MAP sensor if you throw that code. I can try to get it to you. Funny though, I did almost everything in your list. Damn near traded my car!!!

The only other problem I've had similar was created by me int the search for the studder. I replaced the main power cable but didn't zip tie it. So my car started to short out under load. I found that the cable would swing back into the pulley. worth a try. also, there is a ground cable on the back side of your heads. Wiggle that wire to make sure it isn't loose. If you fix it send me $1.43 and keep the change.

**TedsB4Csled** · 11-27-2009, 02:52 AM

Originally Posted by RealLiveMD

I had two vacuum leaks. Coming from the back of the intake manifold, there is a MAP sensor. In that area there is one hose that use to hook to your AIR. Make sure that it is capped off. The second hose snakes fromt he back of the manifold over to the passenger fender well. It then becomes bundled in a wiring harness. The harness snakes into a hole that is between the battery compartment and the front bumper. The hose then snakes under the batterry tray into a round plastic about 8 inch container. My hose was corroded at the level of the battery tray. When the engine moved certain ways like WOT it would torque and seal the leak. Then while driving normally it would studder. I feel your pain. The container is only about 10 bucks at napa.

If this doesn't work. swap maf's with one of your buddies for a week. I have a brand new MAP sensor if you throw that code. I can try to get it to you. Funny though, I did almost everything in your list. Damn near traded my car!!!

The only other problem I've had similar was created by me int the search for the studder. I replaced the main power cable but didn't zip tie it. So my car started to short out under load. I found that the cable would swing back into the pulley. worth a try. also, there is a ground cable on the back side of your heads. Wiggle that wire to make sure it isn't loose. If you fix it send me $1.43 and keep the change.

I'm pretty sure I capped the AIR off, but had the prob long before I unhooked it. I have a spare MAF. I'll check the hose and under the batt too. Yea been ready to burn the thing! Thanks! lol.

**TedsB4Csled** · 11-29-2009, 05:32 AM

Originally Posted by RealLiveMD

... The hose then snakes under the batterry tray into a round plastic about 8 inch container. My hose was corroded at the level of the battery tray. When the engine moved certain ways like WOT it would torque and seal the leak. Then while driving normally it would studder. I feel your pain. The container is only about 10 bucks at napa....

I took out the battery, battery tray and coolant reservoir but there's no 8 inch container. I can see the horn. What this container and what does it do? I have pics on my cell pone. I did find the plastic vacuum hose. Maybe it is cracked somewhere? Waiting on Crank Position Sensor(CPS).

**RealLiveMD** · 11-29-2009, 07:29 AM

Originally Posted by TedsB4Csled

I took out the battery, battery tray and coolant reservoir but there's no 8 inch container. I can see the horn. What this container and what does it do? I have pics on my cell pone. I did find the plastic vacuum hose. Maybe it is cracked somewhere? Waiting on Crank Position Sensor(CPS).

You are looking from the top. Look from the bottom. The canister bolts in place under the metal that the battery tray sits on. It is cylindrical and about 8in and black. I think they called it an ac vacuum canister. The canister shouldnit be the problem though. It's probably the plastic hose. Give the hose a tug and if it comes loose, use some radiator hose to connect it.

**RealLiveMD** · 11-29-2009, 07:30 AM

cps is probably not the answer. seems like it would throw a code or something.

**TedsB4Csled** · 12-05-2009, 08:00 AM

Cold and snowy here. Guess I'll wait to clean the MAF. Can you take SLP MAF apart easily? Waiting on crankshaft position sensor too.

**TedsB4Csled** · 12-05-2009, 08:02 AM

Originally Posted by RealLiveMD

cps is probably not the answer. seems like it would throw a code or something.

At this point it couldn't hurt to try.

**TedsB4Csled** · 12-09-2009, 11:08 AM

Well I got the CKP sensor, but it looks like I will have to take the starter off. So I decided to clean the MAF. Just finished, let's see what happens this week. Please God! Let this be it!

**Frost** · 12-09-2009, 12:06 PM

Don't touch your crank sensor! Simple removal can lead to having to take the car to a dealership for a crank-relearn with a TechII.

There is no point in changing parts here and there on a guess though.

Try unplugging your MAF (before startup) and start the car. Let it warm up and drive it and see if it does it in SD.

**TedsB4Csled** · 12-09-2009, 01:01 PM

Originally Posted by Frost

Don't touch your crank sensor! Simple removal can lead to having to take the car to a dealership for a crank-relearn with a TechII.

There is no point in changing parts here and there on a guess though.

Try unplugging your MAF (before startup) and start the car. Let it warm up and drive it and see if it does it in SD.

Wow. Good to know! I will try your suggestion this week. The car ran fine all day, even before I tried MAF clean. Dirty K&N air filter, so I need to replace it with paper one. Thanks!!!!!!!!!

**TedsB4Csled** · 12-09-2009, 05:47 PM

I will not sell or trade this car. It will be a constant reminder to NEVER EVER EVER modify a car, buy a sports car or Chevy(or Ford). Miss my Subaru and Acura

Thanks for all the folks here, and shops, that tried to help. I appreciate that more than anything. Happy Holidays!

**Wesman** · 12-09-2009, 06:30 PM

Originally Posted by TedsB4Csled

I will not sell or trade this car. It will be a constant reminder to NEVER EVER EVER modify a car, buy a sports car or Chevy(or Ford). Miss my Subaru and Acura

Thanks for all the folks here, and shops, that tried to help. I appreciate that more than anything. Happy Holidays!

I hope you're kidding. You have a very unique problem that is not common to other cars. GM powertrain electronics are some of the most straight forward systems to work with.

Having worked with both Subaru and Acura engines and electronics first hand, I can tell you they are cheap garbage. Honda is so cheap that they still use speed density on most of their engines, and they use the same harness plugs for almost every component because its cheaper. Not to mention the paper gaskets and leaking head gaskets and cam seals every 75K miles (Subaru). I just did one this week that had a misfire on cylinder 3 due to a misadjusted valvetrain, yet the ECU was reporting a cylinder 4 misfire, but cylinder 4 was fine. They are cheaply engineered so they can save money on powertrain costs.

Sounds like you just need to get it to someone that actually knows what they are doing and can diagnose it properly once and for all. Get it on the dyno with HP tuners, monitor all the parameters, and see whats throwing it off. Throwing parts at it is going to do nothing else than get you frustrated and make you go broke.

**TedsB4Csled** · 12-09-2009, 07:34 PM

Originally Posted by Wesman

I hope you're kidding. You have a very unique problem that is not common to other cars. GM powertrain electronics are some of the most straight forward systems to work with.

Having worked with both Subaru and Acura engines and electronics first hand, I can tell you they are cheap garbage. Honda is so cheap that they still use speed density on most of their engines, and they use the same harness plugs for almost every component because its cheaper. Not to mention the paper gaskets and leaking head gaskets and cam seals every 75K miles (Subaru). I just did one this week that had a misfire on cylinder 3 due to a misadjusted valvetrain, yet the ECU was reporting a cylinder 4 misfire, but cylinder 4 was fine. They are cheaply engineered so they can save money on powertrain costs.

Sounds like you just need to get it to someone that actually knows what they are doing and can diagnose it properly once and for all. Get it on the dyno with HP tuners, monitor all the parameters, and see whats throwing it off. Throwing parts at it is going to do nothing else than get you frustrated and make you go broke.

I have had at dealerships, speed shops, brought it to a reputable tuner 2x. There are no codes thrown. The only thing to do IS throw parts at it. I've researched for hours almost daily for almost a year. Asked everyone, and keep bringing it to shops. It should be very straight forward, you are correct, but no luck. One very reputable mechanic had a similar problem and said he had to get rid of the car, he was throwing parts at it at the end too. He never found the problem. My car has very few mods. I have had better luck with foreign cars, much as I would rather drive American. I'm happy ppl get to enjoy their Camaros, but I have been miserable. I'm shocked no one can figure it out, maybe they don't care? Maybe I keep missing something? I learned a lot, and fixed many LS1s that my friends own the last 2 yrs....while in a wheelchair...but my mine is a studdering nightmare at this point.