Losing power at wot at the drag strip

**speedfreak1** · 09-30-2012, 07:05 AM

Hi I took my 99 ta with 199,000 miles on it to the drag strip yesterday and it ran good most of the way down the track. but when i hit third gear and started getting up in the rpms it would die out for a moment and then go again. it runs good at high speed on the freeway. it is a a4 car basicly stock except for magnaflow catback and someone before me put a slp maf. i think it may be the fuel pump but not sure. any suggestions would be helpfull. thank you for any help.

**Spikito** · 09-30-2012, 07:43 AM

just how many RPMs are we talking? could have hit the rev limiter, considering you are stock

**tatertot91** · 09-30-2012, 09:54 AM

Fuel pump could be the cause, when is the last time you changed the fuel filter. I'd also source out a stock maf sensor, you'd be better off than the SLP one.

**speedfreak1** · 09-30-2012, 04:42 PM

The filter was replaced 6 months ago. It cut out around 5,000 rpm was breaking up a little before it cut out.

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**tatertot91** · 09-30-2012, 04:46 PM

Have you checked pressure at the rail?

**speedfreak1** · 09-30-2012, 05:22 PM

I am going to start checking things tomorrow. it ran hard thru first and second and I did 3 runs and every time I had problems only once I hit 3rd gear. seemed to lean out. once I let off and got in it again it ran ok strange problem. could only get a 14.1@98mph due too that problem. I will check fuel pressure and pull some plugs and hook up a scan tool to see if there is anything there but my check engine light is not on. thanks for the suggestions I will post what I find out tomorrow.

**tatertot91** · 09-30-2012, 05:28 PM

Sounds good, could be a good idea to pick up some maf cleaner and clean your maf as well. It's been known to cause all sorts of odd issues when it's dirty

**speedfreak1** · 09-30-2012, 05:53 PM

race-1 video by speedfreak110 - Photobucket

**speedfreak1** · 09-30-2012, 05:57 PM

I was thinking if I do not find anything wrong maybe the previous owners tried messing with the tune. maybe I will send it to frost and get it done right.

**tatertot91** · 09-30-2012, 06:27 PM

Is it the first time it's ever happened?

**speedfreak1** · 09-30-2012, 06:37 PM

it was the first time i really went up to 5,000 rpm in 3rd gear. I got the car a little over a year ago and been taking it easy on it because of the miles on it. I cruise at some high speeds once in awhile but never kicked in down into 3rd. been letting off and letting it shift at around 4500.

**speedfreak1** · 09-30-2012, 07:57 PM

3 of my o2 sensors are reading all over the place 0.90-.0800 and just one stays around 0.770 steady at 1,000 rpm is this normal. advance was at 41 degrees at 2500. just tested this a few minute ago.

**cobra12345** · 09-30-2012, 08:58 PM

2 upsteam o2s should cycle alot the rears it dont matter

**tatertot91** · 09-30-2012, 09:02 PM

They are supposed to fluxuate, thats normal. Which sensor wasn't?

**speedfreak1** · 10-01-2012, 03:57 PM

Ok did not check the fuel pressure yet or pull any plugs. But the o2 sensor that does not change is on the passenger side after the cat. I am going out to check plugs and fuel pressure in a few. thanks

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**tatertot91** · 10-01-2012, 09:52 PM

The upstream sensors are the ones that have an affect on how the engine runs so that's not your problem.

**speedfreak1** · 10-02-2012, 07:18 AM

I checked the fuel pressure and its at 58 at idle and stays there when i run the rpm's up to about 2500. pulled a plug from each side not much color on them and they have around 16,000 miles on them. also noticed a half inch spacer between the throtle body and the intake. I think that slp maf is causeing it to lean out. when the rain stops i am going to tape the fuel pressure gauge to the windshield and see how it holds up under a load

**SMWS6TA** · 10-02-2012, 09:05 AM

lose the spacer and see if that helps

***Firebirdjones*** · 10-02-2012, 11:41 AM

Originally Posted by speedfreak1

I am going to start checking things tomorrow. it ran hard thru first and second and I did 3 runs and every time I had problems only once I hit 3rd gear. seemed to lean out. once I let off and got in it again it ran ok strange problem.

Originally Posted by speedfreak1

I checked the fuel pressure and its at 58 at idle and stays there when i run the rpm's up to about 2500. i am going to tape the fuel pressure gauge to the windshield and see how it holds up under a load

Now you have the right idea. Sounds like classic fuel pressure issues. It won't show a low reading unless you load the engine. Typical to run out of fuel at the top of high gear if you have a weak pump or something else clogging the system. It's the long high gear pull when these issues generally occur as that's when the pump has to work the hardest to keep up. Short bursts through first and second gear (where rpm climbs quickly) in most cases isn't enough to drain the system.

The problem is duplicating it on the street without getting caught

**speedfreak1** · 10-02-2012, 07:38 PM

I kinda of think its the fuel pump because it does not look like the tank has ever been off just was hoping for something easier lol. thanks for all the suggestions i guess when i run it with the fuel pressure gauge hooked up that will tell me its time for some fun. I will try this weekend and post the results.