97 GTP Stuttering/Cutting out at low rpms

[logan809]

Hey,

Ive searched all over and i cant find a solution to my problem. My 97 gtp has 199k, (yes i know alot) and was bought at an auction so i have limited knowledge of the history of the car. It does have an SLP CAI but it stock other than than that i know of. When it revs from idle to ~3200-3500 rpms it stutters and cuts out. I am getting terrible mileage (14 town 19 hwy). I originally thought it was a clogged catalytic converter, so i now have a completely hollow cat. Wasnt the problem. I checked the plugs which didnt seem too bad and were gapped fine. I have read online that it can be a vacuum leak, which i dont think it is, and the most obvious would be plugs/wires. But anyone else who has/had this issue, feedback would be greatly appreciated.

[Iceman6669]

I had a very similar issue with my 97 GTP. I did the plugs and was going to do the wires when I decided to delete the EGR valve. After the EGR delete mod all my problems went away. PS a good way to check for vac leaks is to use carb cleaner or Either and spray it around the vac lines while the car is running. IF you get a spike in RPMs then you have found your leak.

[Regalgs98]

is it throwing a check light? Usually if its my plugs or wires on my regal its about 3.5k or 4k rpm before it misses or cuts out.

[logan809]

It isnt throwing any codes or lights. We scanned it with a very expensive scanner and still nothing. However, we did not do an injector test while we had the scanner and we think that could be the problem. Anyone ever had to replace an injector(s)?

[darkhorizon]

I would use the scanner to see what cyl's are misfiring... If it is all of them, then you probably have a fueling issue.

[Regalgs98]

yeah, a cheap scanner will even say you have a misfire so i'd look to see. Start with plugs in what cyl's it says misfired. If plugs don't cure it go to injectors. I'm thinking after 180k i'm looking to replace mine anyways. If you do i would buy a whole set from a place like zzp. Its i think about 60ea from the parts store.

[logan809]

Still haven't found a solution....just put 6 new plugs and a new fuel filter on and it ran a tiny bit better but neither were the problem. Also has a hollow cat haha. I did talk to another friend that said it sounded like a compression issue so I started looking around and found a small bit of coolant in the galleys below the supercharger by the #1 injector. It doesn't run hot at all but does still run like sh!! At low rpms. Seems to be getting worse...any help still appreciated.

[Scottydoggs]

your lim gasket is shot. my lim also had coolant in the lower intake bolt valleys.

best bet is to get a pressure test done on the cooling system, if it loses pressure, its leaking, but the coolant in the bolt valleys is not a good sign.

[Slick2500]

I would try to seafoam the engine.

[logan809]

Oh and i have no vacuum leaks.

I have ran a full can of seafoam through it already and it did nothing...the lim gasket would explain the coolant, but would it cause the stuttering?

[Slick2500]

Did you do it this way? Grand Prixs Of North America • View topic - Seafoam writeup

[Scottydoggs]

is your coolant always low, just a little bit? like 2 cups worth?

i was topping off my rad, every week or more, found the puddles in the bolt valleys, my plan is to get another engine and mod the crap out of it, so what i did was, i got a jar of bars stop leak, the copper lim and block sealer, and all my puddles dried up in 2 weeks, haven't added coolant in 2 months now too, and the car runs great, but i dont really recommend doing that if you plan on keeping this engine for the long haul.

[logan809]

My coolant is almost never low. Wonder how easy an LIM gasket replacement is.

[Scottydoggs]

My coolant is almost never low. Wonder how easy an LIM gasket replacement is.

if you never did one before it is said to be done in a Saturday, if you know what you are doing 2 to 3 hours, depends on your skill level, and how many you have done in the past helps as well.

heres a link to a vid "lifters in 33 minutes" not really but thats how long the vid is. its the same job minus the rockers and lifters. http://www.cpaclubgp.com/misc/lim-gasket.html

[BillBoost37]

your lim gasket is shot. my lim also had coolant in the lower intake bolt valleys.

Actually, the LIM gasket has nothing to do with the bolt hole areas filling with coolant. Reason being is that our LIM bolts protrude into the coolant jacket and the oil return areas of the motor. Therefore if the sealant on the bolts becomes compromised, the fluid can seep up the threads and out onto the LIM.

While the fix typically includes changing out a LIM gasket. The gasket itself is not the cause and if you don't clean and seal the bolts, they will leak after an LIM gasket job is completed.

[Regalgs98]

if it was your lower intake manifold gasket it would blow out within a year most likely. Thats why i have a different engine now myself. Blew it at 80mph on the strip. Found oil and coolant mixed in the heads and blower passage, it had cracked in two places on the front bank. I should of got the message from the constant loss of coolant and pretty much overheating problem once a month i couldn't cure.

[Scottydoggs]

Actually, the LIM gasket has nothing to do with the bolt hole areas filling with coolant. Reason being is that our LIM bolts protrude into the coolant jacket and the oil return areas of the motor. Therefore if the sealant on the bolts becomes compromised, the fluid can seep up the threads and out onto the LIM.

i guess thats why the bars stop leak worked so well, i haven't lost a drop of coolant in months now, and my lim bolts are dry. car did idle smoother and feels like it ran better after it sealed up too.

[Regalgs98]

be aware, usually run best before they pop. when mine blew it was around 75-80mph, normal 1/4 speed was 98-99 at the time. I still ran a 14.5@93mph with 3 spun rod bearings.

[mrfreez]

You need to do an engine compression test. There's also kits out there that check for exhaust gas in your rad. You should also do a fuel pressure test too; to rule out the fuel pump.

[graygoose698787]

so im having the same issue i wanna do the egr delete but i need to know one is it safe will the car produce future issues and 2 what all is involved in doin this