New here... and having some problems with my '02 GT

hey everyone, i'm new to the forums. i've owned my '02 Mustang GT since she was new, and after graduating from college in december decided to finally put a blower on it. i put a Vortech on my stock motor and ran it like that for quite a while with no issues whatsoever. about 2 months ago i rolled through some high water (long story..), and since my air filter is about as low as you can imagine in the passenger front fender, it sucked water in and hydrolock literally destroyed my rods... so it was time for a rebuild. (the car was never submerged and i literally rolled right through this spot of water and came out about 2 seconds later on dry land)

ever since the rebuild, i've had trouble with a very inconsistent a/f ratio. the dyno pulls showed a solid 11.5:1, but not too long after i got it on the street i started having problems. first off, before the engine is warmed up, it idles so damn rough i have to hold the revs at 1500 rpm just to keep it from dying out. the whole car shakes, the motor sounds like *****, it literally feels like it's running on about 6 or 7 cylinders. after it's warmed up a few minutes it miraculously returns to normal.

once i get out and start driving, while cruising (cruise control, flat road with no incline/decline) my a/f holds pretty steady between 13.5:1 and 14:1, and then will randomly drop down to 11:1 (or lower). after a few minutes it'll randomly lean back out and run fine.

i can make full throttle pulls through 1st and 2nd gear, but in 3rd and 4th gear when i hit around 4000 rpm my a/f goes extremely rich (so rich my digital a/f gauge won't register it) and it literally hits a wall and just won't rev any higher. it didn't do this at all on the dyno in 4th gear. even more confusing, i put it in 4th gear and crept up on 4k at part throttle, and then mashed the throttle at 4200 and it pulled all the way to 6500 before i let off.

does this sound like a bad maf or possibly a fuel injector getting stuck open? i'm wondering if injesting the water may have ruined the maf, i've been considering getting an Abaco DBX if this is the case. is there a way to test for a bad maf or bad injectors? i'd hate to just start buying stuff in hopes that i'll pinpoint the problem that way.. i've already put enough money into it and don't want to have to spend more if i don't have to. i'd really appreciate any help you guys can provide.

Sounds to me like you need your o2 sensors replaced, is it throwing any codes?

Larry

nope, not throwing any codes. and the first thing i replaced were the O2 sensors.. with no luck.

it wasn't much water at all. it had been raining and i was going under an overpass. the water was a few inches deep so we were rolling through it real slow (cars in front and behind me, no shoulder, nowhere to go, etc), and then suddenly the road dipped down and then right back up. i'd say the water was maybe a foot, possibly 18 inches deep. i rolled through it and then right up an incline to dry ground so the car wasn't submerged or anything, and i rolled through it for maybe a second, possibly a second and a half. my air filter is really low in the fender so it didn't take very high water for the filter to get wet.

my engine builder said it sounds like either a stuck injector or a bad maf... this is my daily driver and i haven't had time to drop it off for him to look at it though, so i'm trying to diagnose it myself if possible. it ran fine on the dyno and for a few days after i picked it up, so he wasn't seeing any of these problems when he was tuning it.

something else i've noticed.. when i start it up cold and it idles real rough, if i pull a vacuum line off the plenum the idle smooths out but jumps to about 2000 rpm. is this normal? i've pretty much ruled out a vacuum or intake leak. it holds a steady 10 in-hg of vacuum at idle (thanks to the cams) and when i make a 2nd gear pull i'm seeing about 10 psi of boost at 6000 rpm.

btw, i went out this morning and took this video while cruising at 60 mph on the highway. the a/f ratio jumps around the low-to-mid 13's, if you jump to about 1:10 and watch from there, it spikes up to 14:1 and then drops down really rich (11.1, 10.9). a few minutes after i stopped recording, it went back up to mid 13's

sorry for the crappy video quality.. didn't have my good camera on me

YouTube - 2002 Mustang GT supercharged

If you sucked up enough water to hydraulic the engine, I'd bet it damaged your maf sensor, since all that water went through it.

+1 on the maf taking damage. Those wires are real senstive, odds are you shorted it out which is why its very sporatic(sp). With that said, I've read great things about the dbx maf's. Might be a great time to upgrade, and quickly before the maf spikes you lean and you pop another motor.

Might check your fuel pressure sensor the big relay looking sensor on your fuel rail diverside? just an idea I replaced mine when I had my engine rebuilt?

yeah i've even heard of some boosted guys keeping a spare fuel rail pressure sensor in their car cause they tend to go out under boost at times. i may try this first as it seems the cheapest option. i already replaced the front O2 sensors to no avail. how much does the fuel rail pressure sensor cost? about $100 or so?

i guess this may be a question for the tech people at Abaco, but i'm looking at their meters and the info on their web site doesn't give a whole lot of detail. i'm looking at the description for the 85mm meter and it says this:

"Designed for small cubic inch engines with suck through meters with 3.5 clamp-on filter or big cubic inch engines with blow through meter applications for turbo or Supercharger using 3 to 3.5 tubing."

not sure if this will work in a "suck through" supercharger application? mine's not currently set up as blow through, although i could cut and splice things if i have to. i've got enough tubing between the aftercooler and the throttle body to install it there. in fact this seems like a better option cause my maf is currently way the hell down in the passenger side fender and i couldn't get to it to plug the usb cable in with the DBX.

thanks for the advice/opinions everyone.. i really appreciate it.

Ive been having the same problems and im leaning towards the MAF....

I will let you guys know if it fixes it tommarow, I should be trying a new meter...I hope.

btw, who does your tuning? is it HP Performance?

+3

The MAF controls ALL of that sh1t...it's randomly jumping AFR....I'd say the MAF is the culprit. Try cleaning it with electrical cleaner.....or replace it...

the maf was cleaned real well during the rebuild, so i'll probably just need to replace it.

does anyone know of a way to test to make sure it's bad before i drop $400+ on a new maf setup?

Matt @ performance evolution in middletown does my tuning.


what setup are running thats 400 dollars?

damn

I thought my HPX sensor was gonna be expensive at like 230

thanks for the info. whenever i get a chance i'll give this a try.

i was looking into the Abaco DBX digital meters, you can tune the a/f directly through the maf itself rather than through the PCM. it has a USB plug to load tunes from a laptop (stores up to 10 tunes). the cheapest one is like $370 and that's before the wiring harness and air filter i believe (they may be included, not sure). i'd love to run this setup, but i just don't think i can afford it right now. if i can find a replacement 90mm Lightning maf then that's probably the way i'm going to go.

EDIT: found a new FRPP Lightning maf on ebay for $85.. $150 with a new air filter. and it's supposedly already calibrated for 42# injectors (which i have). pretty sure i'm going to go this route if it is a bad maf.

is there a way to test the fuel injectors? i've heard of people holding a stethoscope to them while the engine's running and supposedly you can hear if one is stuck open (or opening and closing inconsistently).

I would do the classic ford wiggle test first, followed by a second mass air cleaning and visual inspection.


Also, by you pulling a vac line and the car smoothing out, you are running too rich.

You need someone with a good scanner that can monitor fuel pressure, 02 reading through the comp, LS and ST fuel trims, tps voltage, IACV voltage while cruising.

You will also be able to see if the misfires are random or just on a few cylinders on the misfire monitor.

hey i noticed that your car runs really cool (tempature), with it running so cool your car will run rich while driving it.