wont go over 4k while driving...

[keithscianna]

Hello,

My 99 GST is acting up. I can not go past 4000 rpm while driving. It just starts bogging down and i start loosing speed. This happens in every gear, I cant go past 80 on the highway. If i let of the gas a little bit and let the boost go down i can go a little faster. While this is happening my stock boost gauge is maxed out. The funny thing is that if i am not in gear i can rev it just fine as high as i want to. I also changed my plugs and wires. I did a boost leak test and there is not a leak. What is going on here?
Some mods i have are as followed,
16g
AEM fuel rail,
greddy bov,
pulleys,
3 in exhaust

thanks,

keith.

 

[stockfornow]

What kind of spark plugs did you put?

 

[keithscianna]

Autolite i belive, gaped to .32. It was doing it before i did the plugs and wires too.

 

[stockfornow]

Please don't tell me that you have used the Autolite spark plug wires too... they are junk. Get something better like NGK, it could be your problem. Also what boost are you running, and do you have bigger fuel pump, and AFPR?

 

[keithscianna]

The wires i used where borg warner. Now when i got the car it already had the mods on it, So i am not sure about the FP and it have a FPR. Should i just pull the pump and see what it is? Or maybe do a fuel pressure test. As for the boost i have a stock guage and when it starts to bog down the guage maxes out. If i let of the gas and relive boost i can get it to a higher rpm, It kninda feels like it is starving for gas.

 

[pooker]

Do us a favor and pull your plugs real quick, I am betting money that your problem might lie there.

 

[romeen]

First things first. Change your plugs to NGK BPR6ES gapped to .028". Maybe a set of plug wires while your at it. NGK's are good for the money. I have had good results with my Accel Thundersports as well.

If you don't know when your fuel filter was last changed then I would recommend doing that as soon as possible.

These are basic maintenance and need to be done occasionaly anyways.

Other things could be causing it but this would be a good place to start.

 

[keithscianna]

well it was doiyng the excat same thing before i changed the plugs.

 

[keithscianna]

Ok i just changed them to NGK's. same thing. It only boggs down when the boost rises. If i just git the gas gently and dont let the boots rise i can go to 7k. What does this mean?

 

[keithscianna]

Also i am running extreamly RICH.... The plugs i put in today and drove 10 miles on are black and coverd in SOOT. what does this mean?
thanks,
keith

 

[pooker]

Sounds like you have a boost leak.

 

[mini zilo]

Something like this happened to my brother... His speed sensor connector on the trans kept coming off, and the ECU thought the car is going 0 MPH, so it rev limits at 4K... Just a possibility. (check the speed sensor)

 

[saintsairforce]

I had the same problem when I bought my 94 laser. Ended up being a bad altenator. The electrical draw from the engine was greater than the altenator could produce and as a result it topped out around 4k and 80km.

To check simply measure the voltage across your battery when the car is idling. It should be 14-15 volts. If it is less then check the altenator belt for wear, tension and cracks. Bring your altenator in for a load test and if it fails then either get a new one of buy the rebuild kit. I lucked out and had a parts car at my house that had a good altenator in it and just did a quick swap and it solved my problem.

Hope this helps,
Ricky

 

[RedTurboEclipse]

stockfornow, romeen

You guys are quick to blame those autolite spark plugs. There is a wiseman here who will recommend them. He runs a big turbo and supporting mods with it. I run the autolite on my beater GSX and have worked fine.

And keith did switch and the problem still arises. It was a good call to check the spark plugs and wires, but it should still allow him to go past 4k, if they were bad they would sutter/bog. As stated and what I would check is for a boost leak. When I had problems like this, that was the main culprit.

 

[silver eclipse]

The stock boost guage isnt really accurate for reading problems.
Like RedTurboEclipse said, they where to quick to jump on the plugs, even when you said it happend before and after the autolights.
The black plug does mean you running rich, did you pull all 4 or just one?
-Chad

 

[MyÜberFastGSX]

There are 3 things an engine needs to run.
1.Fuel
2.Air
3.Spark

If you're plugs and wires are fine, then back track the electrical system. Check the coil pack, etc. If you're firing system is fine, then check the fuel system. Do a fuel pressure test. If that's good, then check to make sure your intake system doesn't have any major blockages.

It could also be the turbo. Because when you're at an idle, the turbo isn't under a load so it doesn't have to work hard. But when it's under load, it sounds like that's when your problem is....

So here's a scenario. Boost Creep. When you punch it, your turbo overboosts, and hit's fuel cut. This theory would be backed by the fact that 1. your boost gauge is maxing out, and 2. if you let off the gas, and therefore, stop boosting, you can get a little more rpm's.

Just a thought.

 

[blackmirage]

Please, Please, Please! Check this for me before you check anything else.. I did EVERYTHING everyone else is telling you to do. I spent all kinds of money on all kinds of things. Mine was doing EXACTLY what yours is now. I spent 95.00 on a non eprom ecu just to make sure if thats what it was and guess what.. IT WAS! Car runs like a dream.. I beg of you before you spend alot of money, check out the ECU.