Hi, I have a 1997 monte carlo LS. I drove fine when I bought it. but after setting in my drive way for a month I now runs rough and won't go over 3k rpms and starts in any gear. It has 0 engine codes and no stored codes, after checking everything I could think of I replaced the maf and it now idles and runs great and will drive up to 90 fine but a little slow as it still won't go over 3000rpms. I dropped the cat and replaced the nutral/park range switch as it was starting in every gear still. Drove it around the block and it now goes a hair over 3000rpms but flooring it stops at 2-2.5k but still starts in every gear. I have a scanner, autel mx808, and it shows is reading every gear. Additionally right turn signal doesn't work so I bought a new switch, and the blend flap is stuck on defrost but the dash lights for the ac/heat are also buggy and stop working randomly but come back on shortly or maybe it's a loose connection. ANY HELP WOULD BE APPRECIATED

 

Lots of issues there. We should probably take it one at a time starting with the most detrimental to driveability - not going over 3k rpm.

Are there any other drivability issues (low on power, misfires, etc)? Do you see anything odd on all the major sensors (via scan tool) when it hits the wall? Is it shifting when it hits 3k or just getting stuck until you ease out of the throttle? Is the rpm exactly consistent or is there some fluctuation (ie one time its 2500, the next is 3500).

Is it a hard stop like its hitting an actual limiter or does it start running worse and worse as it approaches it (ie like a misfire that gets substantially worse with rpm).

There is a possibility its tied to the gear issue. The pcm has a different rev limit for P/N (although 3k sounds a bit low for that) so if the car runs 100% fine and is hitting a hard limiter a the exact same rpm each time, its possible the pcm is getting confused and enacting the P/N limiter. If you think thats the case, you could try revving it in P/N to see if the engine stops at the exact same rpm. If it does, we could ignore this issue and move straight to fixing the gear issue.

 

No driveability issues daily drives fine, Computer shows no misfire and its a hard limit, no bogging or missing out. Same in park as it is in every gear and will shift before 3000rpm fine if not throttling to hard but won't shift without letting off if giving too much gas. Computer doesn't show any more issues when at hard limit but motor shakes mounts pretty hard. And yes if I floor it I only get 2k-2.5k and it fluctuates a little bit each time.

I installed a new p/n safety switch as I thought that was my issue but when the switch was supposed to be in nutral I had to have the tranny in reverse to slide it on. Thought I may have turned it somehow before trying to slide it on. Even after replacing it, the car still starts in every gear.

and new problems, broke an vacuum line, replacedit but joe my blend flap changes to defrost when accelerating

 

Thanks for the help, found out the problem and looks like I have some work cut out for me. The relays that controls the p/n switch, ignition, door lock, anti-theft, and everything in the dash was cut out, rewired directly, and crimped together. Along with a mess of wires that look like a 9yo did them. But removed the crimped wires on the p/n switch relay and car won't start tell reconnected. Going to have to remove the dash some time and find the surprise of a wiring job to look forward too. But after fixing most of the door, security, and relay issues the car stopped cutting power and went 80 down the road. Was still running ruff and cutting out at low speeds but on my way to town today at about 65mph the exhaust claim I used blew off and I thought I had a tire but looks like after all the rain and floods this week I had water in my cat and exhaust and it plugged up and blew apart my couplers. So overall I appreciate everybody's help and everything that was said was all partly right, it was wires and plugs, electric shorts, relays, fuse, maf, egr, vacuum, and bad cat.

 

Man, that's a rough break! Glad to hear you found it though, but I certainly don't envy you having to fix it all.

 

Ok, so I'm back. I was hopping everything was fixed but just drove across country and found out its not completely fixed. I think k I have the wiring fixed but I need help with 2 things. So the issue is that now it won't go over 45000rpm and that I need some wiring help for the glove box. I have found a connector behind the glove box that's been cut out and without crossing the larger wires the car doesn't start. It's a 4 wire connector for what I assume was the p/n or theft relay. Also when it hits the 4.5k limit it start popping/backfiring. Not sure where to look. It still has a vacuum leak as I lose front vents when accelerating but it's a lot better now after fixing the electrical issues I have found. Any advice would be great. Also the relay is a lage purple and yellow wire, and 2 smaller Yellow wires

 

Any pics of the wiring you're taking about?

Given the wiring was hacked up so bad, have you thought about a complete harness swap? Id be worried there could be more issues you have found yet if its hacked up that bad.

Any idea why it was hacked up in the first place (mouse damage, modifications, etc)?

 

Definitely crappy YouTube modifications and shady mechanics

 

If anyone can help me figure out what this Controlled or a diagram so I can get a matching relay. Thanks much