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Problems. HELP???

J

JBRGT13

New member
So recently, I purchased a POS Grand Prix from a private seller for a winter project. The engine has about 250,000 miles on it, Standard 3.8 V6.
And after driving it for maybe 15-20 miles, I've noticed some problems.
1.)Engine does not always want to start
2.)If I have it in park and rev the engine a bit, to about 3500-4000 RPMs, after I let off the accelerator it will drop to about 500 RPMs and die.
but does start right back up
3.)When I start up and put it in drive, it sometimes sputters and jerks its way forward until I stop, put it in park, shift back in drive, and take off again.


I know I'm going to have to replace the engine, but I'm looking for info as to why these problems happen.
Spare some time and advice for an aspiring mechanic?
 


All of those things sound like sypmtoms of a vaccuum leak. Its probably an intake manifold gasket or cracked vac lines.

If you're planning on keeping the car for a while after the swap, I would reccomend redoing everything from the head gaskets up on the new motor.
 
Can you give me a part specific list? Or something to that effect? This is the first big project I've ever taken on.
Thanks for the reply!
 
And I should drop all that into the new engine? I was planning on putting in the 3.8L engine with a supercharger this time if I can find one for the right price. Also looking into putting the Secret Weapon Cold Air Intake. This is going to be a big project. probably take about a year. But I've always loved the Grand Prix body. So it's worth it to me. I'm pretty much planning on replacing the whole car haha. Piece By Piece. Also. Will the regular GT Tranny(w/o Supercharger) Fit a engine with a supercharger on it?
 
I would avoid a secret weapon cold air. You can make your own and save some cash, and use a better filter.

The trans will work, but you will need a custom tune.

Browse around, there are a ton of threads on how to make power in a 3800. If you do a lot of reading before you start buying parts, you should be fine. I usually make a spreadsheet with retail prices, part numbers, etc. It helps visualize what you need and how much its going to cost, then while you're waiting for the build, you can usually find cheap used parts on the forum.

If you're trying to make it a racecar, you may want to explore other platforms before committing. A custom trans is going to run you about $5k.
 


Not really looking to make a race car. As much as something me and a friend can work on and be proud of when it gets done. And As for the custom Transmission. Not really looking for anything too awesome. Just one that hooks up to the engine. I can get a Engine and tranny for my make model and year exact. for 750.00. but thats without the supercharger. and honestly. I'd be just as happy with a used 3.8 w/o sc. Just thought if I could find one for a similar price. why not? I mean. I only payed 450.00 doe the car haha. so its worth putting some money into.
 
If you can find a good condition S/C engine, you'd be ok without rebuilding it. I think the last engine I got, I pulled it myself and paid around $200. It had around 112k miles on it. It ran fine, never leaked, etc.

You can pick up a used HPTuner for around $300 then buy credits for your vin for $100 and tune it however you want it as long as you have it. HPT works on pretty much any late model Chevy/ Ford/ Dodge, so what you would be learning could benefit you down the road as well.

As far as a specific tune for a supercharged motor, it should be as simple as matching the S/C engine map to your stock transmission map. I'm sure someone here could help you out more when that time comes.
 
Yeah. I don't have a ton of cash at the moment. Which is why I'm looking for the best deal. And though I've never really worked on a project this large, I'm dedicated to doing this without sending it to a shop. That's not even so much about the money as it is for the sake of having a project. So it's for sure going to be a learning expierience. I'm not terribly concerned with the power, It's pushing almost 200 hp stock. So a cold air filter and improved exaust will probably be enough HP for me anyway. Just trying to nip some problems before I worry about making it look nice. Engine and tranny being the first.
 
3800s are pretty forgiving, so you should be ok whichever route you go. Since you're tight on cash, I would just drop a Naturally Aspirated motor back in it, that way you won't need a tune. You can always topswap or turbo later if you choose to do so.

Stock exhaust isn't restrictive until basement 13 second quarter mile times, so I wouldn't bother with it. 3800s sould like crap with flowing exhaust anyway.

Check this link out:
http://www.grandprixforums.net/showthread.php?t=67580
 


Just ran down to O'Reileys today and had them check the engine light. Says it's a mass air flow sensor. Does that check out? Did not give me the exact code. But he did say that the code for the MAF sensor kept repeating itself.
 
And you were talking about Top-Swapping the engine earlier, I can't seem to find a guide online for that. What does it involve. If I'm correct in what I was looking up, I can get the supercharged head for $150.00. What else goes into it? What kind of bill am I looking at if I wanted to do it myself. Also for the MAF, Am i better off just going with a new sensor? Or if I should use cleaner, what brand and where should a clean?
 


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