JGA

Hi

98 A4
K&N induction
Mac Headers
Mac cat y pipe
Borla cat back
MSD coils

Recent compression test was excellent. Car runs fine. No engine codes. New plugs and wires. New cats.

Dyno results:

A/F = 12.6 @ 3800 RPM
A/F = 13.0 @ 4600

peak hp = 243
peak torque = 275
Mustang dyno

I expected atleast 300 HP at rear wheels. What to check?

torque converter lock up
knock sensor
fuel pressure
throttle body open
Dyno service out to lunch?

Any comments or help appreciated.

JA

Blacker

iTrader: (3)

That is to be expected from a Mustang dyno. They will dyno much lower than a Dynojet. 98's are the lower dynoing models especially the A4's. The TC doesn't lock on the dyno unless you specifically programmed it to do so. Maybe you can post the graph and then we can get a better interpretation of what is going on. Might try to find a Dynojet in your area and go from there.

Doc

iTrader: (9)

After having bought my car off the showroom floor in 98 and waited till 2002 to start modding-(I had a job that had me travelling so it just sat in the garage). I finally got it to a dyno around Thanksgiving- a DynoJet. I have the following mods...

FRA
BBK 80MM TB
SLP 85MM MAF
TR55'S
GROTY LT'S
RT CATS
3" Y PIPE
SLOWMASTER 80 SERIES
TCI 3K STALL
RAPTOR 4L60E
HPP3-FOR SHIFT PTS AND FANS

The Dynojet said I had 305 / 305 hp, tq. The place that I went to was a Ford place- they didn't have software to lock the converter. All the GM autos that day seemed kinda low. However I am throwing down on tuning software and a wideband with some exhaust mods to help out. 245 seems low for a car that seems to be working right like you explained. Do you have any timeslips? I am going to the track for the first time next saturday.

JGA

Hi

No time slips as there are no 1/4 tracks in my area. Only one dyno I know of and it is this Mustang. I will try and get the graph scanned and posted. I did not know you need to lock up the converter with software. I don't think the dyno shop new this either. t

There is a little more history to this. They did 4 pulls. My graph has the first and fourth pull on it.

The first pull was crazy lean. The graph looks like a seismic event. They stoped and did a scan and everything was working (no codes). They did 2 more pulls and the A/F dropped into line at about 13 on the fourth pull. They told me I had been driving it too slow lately and computer needed to relearn. On the fourth pull the A/F graph looks quite typical, starting at 14.7 and then dropping down to between 12.6 to 13 as the RPM goes up. I was happy to see this.

I do not know if they were shitting me about the PCM having to relearn. They seemed to be screwing around alot with the exhaust probes and they were having trouble getting past the tranny kickdown when making the pulls. I have a feeling they waisted alot of time and wanted to get me off the dyno quickly.

The graph only goes up to 4725 RPM, which is where they claim the peak HP (243) occures. I asked them why it only goes to 4725 and they said it had already had reached peak HP, so the rest of the graph was not needed. I have looked at several graphs on this site and for a stock/minor bolt on 98 car, peak HP is usually in the mid 5000 RPM. So perhaps the graph is still rising and the not showing additonal HP.

Anyway I think the whole thing is a write off and I need to find anouther service. Awaist of 150 bucks.

Thanks JA

Doc

iTrader: (9)

I am sorry to hear that. I do not know everything but 150 for 4 pulls seems steep- unless it is the only dyno in town. You mentioned something about jocking the sensor... I take it you still have all emissions on the car-esp the cats?!? If so, trying to obtain a afr via yer tail pipe with a cat car is about worthless if your cats are doing their job.

JGA

Hi

Yes, I thought 150 was alot too. I assume the right way is with a wide band sensor installed in the exhaust infrot of the cat. I know this for next time. Thanks.

JA

Blacker

iTrader: (3)

The peak horsepower should occur ~5200 rpm, with stock heads/cam. You need to find another dyno and forget it. With the A4, you will have to be over 3,000 rpm in 3rd to start the pull. Better yet, get HP Tuners and manually keep the car in 3rd without the worry of downshifting. I took my car to a dyno awhile back and lost a bunch of power since they did not strap the car down tight enough. The placement of the WBO2 is critical. With some catbacks, the exhaust flow is different through each tailpipe. Random Technology Catback being a great example. At WOT, the cats are not doing anything and do not effect the WBO2 sensor reading by much. The gases are travelling too fast to be catalzed at WOT. Still, the best reading will be prior to the cats.

JGA

Hi

Thanks

JA

wait4me

iTrader: (10)

Check your coils. I have found several to be bad on those msd ones.. Put in your stock ones and redyno it.