Car hits "early" rev limiter

**GottaHaveLS1** · 08-07-2009, 11:56 AM

So i finally thought my car was in perfect running condition after a new clutch and slave cylinder install, but this is not true. I think the engine is running fine cuz I got rid of all my SES codes and got a full tune but heres the problem.

When i got my car tuned, my tuner told me I had my rev limiter set at 6700 rpms and it will rev that high but when I get on it, the car hits an "early" rev limiter. Its hard to describe but at around 4000 rpms it sounds like it hits the rev limiter and i let off the gas. It seems to only do it in first or second gear... I haven't had many chances to go faster. When i had my stock clutch, i thought it was cuz it was slipping (it had 74,000 miles on it) so i got the ls7 clutch and a new slave but it still does the same thing! It would also do the same thing when I did burn outs but I haven't done one in a while cuz i'm still breaking in the clutch. what the hell could be wrong with my car??? Could it be the stock master cylinder going bad?

**NoscamaroSS** · 08-07-2009, 01:29 PM

I would do a tune up on it. It sounds to me that you need to change the fuel filter.

**Wesman** · 08-07-2009, 01:42 PM

Doesn't sound like a clutch related issue at all.

Sounds to me like you're either losing fuel pressure or losing spark. When was the last time you did a tune up?? If not recently, I would start with wires and plugs. When you put a load on the ignition system and you have worn components, you get a misfire which feels similar to hitting the rev limiter.

If your plugs and wires are fine, I'd check out the fuel system next. As noscamaross mentioned, change the fuel filter first. If that doesn't do it, you'll need to check fuel pressure and see if maybe your pump needs to be replaced.

**GottaHaveLS1** · 08-07-2009, 02:41 PM

Originally Posted by Wesman

Doesn't sound like a clutch related issue at all.

Sounds to me like you're either losing fuel pressure or losing spark. When was the last time you did a tune up?? If not recently, I would start with wires and plugs. When you put a load on the ignition system and you have worn components, you get a misfire which feels similar to hitting the rev limiter.

If your plugs and wires are fine, I'd check out the fuel system next. As noscamaross mentioned, change the fuel filter first. If that doesn't do it, you'll need to check fuel pressure and see if maybe your pump needs to be replaced.

i've been getting "tune ups" on my car all summer. let me explain what I've done.

1. Fuel - I just put a new fuel filter in it last week, the fuel pump is also new from last summer and has only been on the car for several thousand miles. I also had the injectors pulled earlier this summer cuz I had low fuel pressure last year and I wanted to rule them out. The injectors turned out to be fine and I've put less than 2000 miles on the car since then.

2. Ignition - I put new spark plugs in this summer.. AC Delco gapped to .05 inches and they have less than 1000 miles on them. I have msd ignition wires that were put on last summer and have less than 3000 miles on them. They're not melted and they're all connected correctly. I guess the only other thing that could be wrong would be a coil pack going bad.

Is there anything else you guys could think of that might cause this? thanks for all your advice!

**Wesman** · 08-07-2009, 03:35 PM

Originally Posted by GottaHaveLS1

i've been getting "tune ups" on my car all summer. let me explain what I've done.

1. Fuel - I just put a new fuel filter in it last week, the fuel pump is also new from last summer and has only been on the car for several thousand miles. I also had the injectors pulled earlier this summer cuz I had low fuel pressure last year and I wanted to rule them out. The injectors turned out to be fine and I've put less than 2000 miles on the car since then.

2. Ignition - I put new spark plugs in this summer.. AC Delco gapped to .05 inches and they have less than 1000 miles on them. I have msd ignition wires that were put on last summer and have less than 3000 miles on them. They're not melted and they're all connected correctly. I guess the only other thing that could be wrong would be a coil pack going bad.

Is there anything else you guys could think of that might cause this? thanks for all your advice!

Your best bet would be to data log. A program like Autotap or a Snap on scan tool would work, but the best would be HP Tuners. That would give you some idea of what is going on - such as what all engine sensors are reading, if the knock sensors are picking up anything, if there are any misfires, ect. That should really help you narrow the problem down. Only issue is getting a hold of a program to use.

**0rion** · 08-07-2009, 11:24 PM

I agree with what everyone else is saying. Sounds like a spark or fuel issue. Start simple and check your wires to make sure they're all on good and none are damaged. Same with the plugs. Might not hurt to pull them and inspect them. Notice any other issues with the car? Any other missing? If the plugs and wires all check out fine I would probably put a fuel gauge on it and drop the hammer and see if your fuel pressure falls on it's face.

**GottaHaveLS1** · 08-08-2009, 06:21 AM

Originally Posted by 0rion

I agree with what everyone else is saying. Sounds like a spark or fuel issue. Start simple and check your wires to make sure they're all on good and none are damaged. Same with the plugs. Might not hurt to pull them and inspect them. Notice any other issues with the car? Any other missing? If the plugs and wires all check out fine I would probably put a fuel gauge on it and drop the hammer and see if your fuel pressure falls on it's face.

I didn't have any other issues with the car until last night. I stopped in a parking lot for a minute to use my phone and when I turned my car back on the lights for the gauges didn't turn on at all. Also, the lights on my stock head unit wouldn't stay on if I turned my lights on but they would turn off if I shut my lights off. This makes me think I'm having some electrical problem and my coilpacks might not be getting enough power to give more spark at higher rpms.

also, I've never been able to find a fuel pressure tester that I could attach to the schrader valve on the fuel rail. the one I bought at autozone wouldn't fit and I couldnt find a different one. I would buy one that is just a gauge that attaches to the rail under the hood but I don't have money or time to spend on that cuz i'll be going back to school in 3 weeks..

Could these two problems be related??

**jaydean21849** · 08-08-2009, 09:24 AM

battery volts too low guages have nothiong to do with coil packs weak battery or bad alternator

**karpetcm** · 08-08-2009, 01:36 PM

Mine is something like yours, mine in 1st and 2nd gear would miss at about 5500 rpms and then 3rd gear and above runs perfectly fine up to 6k. Its fairly consistant as well and this happened right after i got it back from my last tune and did not notice this at all before. I think it might be the tune for LT's and i havent yet put the LT's on and that might be causing it. I cant think of anything else since it ran perfect before the tune, so i think it might be running a bit rich or too lean.

**GottaHaveLS1** · 08-10-2009, 04:37 PM

Originally Posted by karpetcm

Mine is something like yours, mine in 1st and 2nd gear would miss at about 5500 rpms and then 3rd gear and above runs perfectly fine up to 6k. Its fairly consistant as well and this happened right after i got it back from my last tune and did not notice this at all before. I think it might be the tune for LT's and i havent yet put the LT's on and that might be causing it. I cant think of anything else since it ran perfect before the tune, so i think it might be running a bit rich or too lean.

hmmm that sounds exactly like what my car is doing. does urs do this under WOT? my car still hits what sounds like a rev limiter on slow acceleration in first and second gear but not in third. I haven't had a chance to go fast enough to see if it does the same thing in fourth....

**Mr. Luos** · 08-10-2009, 07:36 PM

Does it rev past the 'lower limiter' while in neutral?

I would check fuel pressure again. At the rail, and if possible, for a WOT pull in 3rd gear.

**karpetcm** · 08-10-2009, 07:49 PM

Mine only does it at WOT in 1st and 2nd gear at about 5500rpms, but in any other driving situation or WOT it runs perfect. My only explanation would be i need to install these headers and see how the car runs. It might run better or worse but ive heard the tune for LT's isnt that drastic to cause it but then again it only happened once i got my tune for LT's. So in fairness i would have to install my LT's and see what happens, my car is really sensitive to tunes, hopefully i can pull some money together and get these headers on. With no job and hardly any experience on cars its just not happening.

**Mr. Luos** · 08-10-2009, 07:50 PM

Stock MAF or aftermarket?

**GottaHaveLS1** · 08-11-2009, 06:56 AM

It's the stock MAF. I'm going to check today how high it revs in neutral... i know i should have done it by now. I would be very surprised if the fuel pressure was low cuz I just dropped the tank last week. The hose inside the pump slipped off the fitting a little bit and it was running like shit. I also have all new high pressure lines that won't kink and a new fuel filter.

**GottaHaveLS1** · 08-11-2009, 07:23 AM

i just revved it up in neutral and it hits the "rev limiter" at 4500. i'm clueless as to what could cause this...

**GottaHaveLS1** · 08-11-2009, 08:30 AM

i just talked to my tuner and this is what he said:

park/neutral rev limiter is set for 4650 rpms, which explains why it does it in neutral.

In gear rev limiter is 6750. Timing is 27+ degrees at WOT and commanded AFR is 12.7. Your problem is not wiuth the tune, it is something mechanical. Best bet is for your to come down (again) and have me take it for a ride and scan it to see what has changed . I'll be able to see if it is fuel pressure. Stock tach would only be off 100 or 200 rpms, but I will also be able to see that in the scan.