loss of power/bogging problems

[Hubes]

i am havign soem weird problems. after my car has been sitting for a while, i give it soem gas and it doens't want to move. it just bogs and then it will catch. when it is warmed up it feels like i ahve a power loss around 3k rpms. it sounds liek the engien is starving for fiel or air and then it catches. this is especially noticable when i floor it. any suggestions on what it could be? i am goign to change the fuel filter tomorrow? fuel pump perhaps? but i need help!

 

[fredhurderjr]

Jay -
I had a similar hestitation on my 91 at about 3k; I never did find out what it was, but I had it with 2 different MAFs & Y-Pipes. I was leaning toward Throttle Position Sensor, or Fuel Pressure Regulator.

 

[Hubes]

thanks fred
the TPS is fairly new (replaced within past 3 months) i just got done doing the fuel filter (figured might as well change it anyways) but have not taken it for a test spin yet. where is the fuel pressure regualtor? right now i am running my stock airbox with stock maf and a fairly nw SS y pipe and cats thet were installed last fall when i bought them brand new

 

[Blast7]

I've been having the same problems but mine also has a little bit of a bouncy idle. I'm going to clean the IAB and see how that works. I"ll let you know.

 

[Hubes]

my iab is brand new....replaced like 2 weeks ago

 

[TopSHO92]

I had the same problem last year around this time. Let me guess? ...it has no power when you use anything above half throttle? Well, that's what mine did... I had the codes pulled, and my MAF was shot. So, I swapped a used one to get me by, and she was like brand new again!!

Best of luck to you! thumbs_u

 

[SHOfear]

Same exact problem here, and guess what it was. Bad fuel injector. Run a compression test, and see if you have a bad cylinder. If you do, replace the fuel injector for that cylinder. That is what I did, and the SHO runs really well.

Steve

 

[naval-avi8or]

BTW~ the fuel pressure reg. is the small round space ship with a vacuum hose on the end of the fuel rail by the crossover tube.

 

[naval-avi8or]

SHOfear:
Same exact problem here, and guess what it was. Bad fuel injector. Run a compression test, and see if you have a bad cylinder. If you do, replace the fuel injector for that cylinder. That is what I did, and the SHO runs really well.

Steve

I think you meant cylinder balance test.

 

[D]

same problem on this end.i pulled the codes and recieved a 551 i.a.c. valve{idle air control}i have the one with the breather so i am unable to clean it.also recieve a maf code and tps code they are fixed just waiting for the i.a.c valve.also cleaned the intake {egr and i.a.c inlet}

also changed my fuel pump,fuel reg,fuel filter.about two weeks ago.

now tell me do i love my sho or what...all this in a mouth.hopfully i'll be all set for a while!!so i can save for my 60 k{65,567}

<small>[ May 10, 2002, 02:33 PM: Message edited by: D ]</small>

 

[edogg23]

Im having that problem I need to check my codes. I ran at the track and my sho was getting 88 mph trap speeds. Holy slow sho!!!

 

[Hubes]

i guess we will see what happens when we pull the codes. hopefully nothing to expensive

 

[John]

Have you done a Full tune up ?
John
91 SHO

 

[stevetatro]

Could be a lot of things, but before replacing parts, rule out certain possibilities.

First, check for codes. I'm sure you already know that. Make sure you do the cylinder balance test during the KOER so you can discount the possibility of a bad injector.

Another thing to try is to unplug your MAF with the engine running. Rumor has it (never tried it myself) that if a bad MAF is causing drivability problems that unplugging it will make the problems disappear (except for a the beautiful CE light). Along these lines you could check and make sure the MAF sensor elements are clean and shiny. These usually only get fouled on cars with over-oiled K&N (and similar) filters.

Good luck. Let us know if you get some codes.

 

[Hubes]

yeah it had a full tune up like 4 weeks ago. it stopped doing it for the past 2 days but when i started up my car this morning it did it for like 15 secs and went away and bang full power again. odd if it does it again i will have the codes read

 

[noSHO]

It could be the CID (Cylinder IDentification sensor, aka cam position sensor). Most people never seem to think of this and are never able to eliminate the problem. Honestly, it is a $40 part, and can be done in probably 2 hours, most likely less if you are good at getting that intake off. When the CID goes bad, it loses track of what cylinder is where, and doesn't know what to do. Consequently the fuel and spark are intermittently cut out, causing the hesitation and bogging. HOWEVER, when the CID goes bad, the hesitation is usually pretty violent, more like a bucking and not a hesitation. If I recall correctly, Scott still has the original CID on his car (at least I think that was the case as of the time I was going to do my 60k a few months ago), but I still wouldn't rule it out as something that could go wrong. It's a pretty easy check, and I think you'd be happy if that is what turned out to be the problem. Good luck getting things back to normal.

 

[Blast7]

Another thing that I did to help my power loss problem was replacing the MAF connector. I'm not really sure if you can test it but it is a $15 part and you just cut the old wires to solder up the new ones.