Has a stumble at 3500 like someone turned the key off

[88foxvert]

running bad at wot 3500rpm.....help

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alright i'm done throwing parts at it .......


Need some help PLease....



88 gt 5 speed stock short block upgraded to 89 cpu harness and a9l/ maf
cleaned all grounds to shiny metal and a touch of dielectric grease too..
idles at 650 -700 steady
new : wire,cap rotor plugs
gt40 -p's w /1.7's fresh and just installed
arp head studs
exploder intake
255lph fuel pump stock afpr 40 psi vacumme off,,,, .
24lb injectors w matching pro-m 80mm maf cali.24s/c
70mm throttle body
10* of timing [spout out]
timing set - set up to [0]
water pump
taurus fan w/ dcc controller
fuel filter
tfI module
tps

soaked the injectors for 3 days in chemtool b-12 and blown out with compessed air backwords then reassembled with new o-rings filters and pintle caps....

sprayed carb cleaner all over engine and vac hoses and connections and it made no difference in idle... has 17 in at Idle and 22-24 when accelerating....

pinched off the fuel return line and fuel pressure goes to 100psi very quickly and engine starts to die......

pinned out maf and connection tested within spec

tps is set to .970 volts and sweeps to 4.5 volts as you go to wot

no check engine light while driving...

now here are the codes from the koeo:

522 vehical not in park or neutral

552 ??? airbag module ????

565 canister purge failure

558 egr vacumme reg failure

542 fuel pump secondary circuit failure

Has a stumble at 3500 like someone turned the key off then comes back to life ...misses hesitates runs like crap at wot but if you ease into it will pull to 4500 then does the same crap........ also after this happens and you get out of the throttle backfires out of the exhaust one time then it seems that at a steady speed below 3500rpms like its dropping a cylinder or two and then clears up..

granny it around and you wouldn't really notice any of this....

changed the injector harness pinned it out before installation(tested good) and its still the same....

egr and smog stuff has been deleted I have the bullit plugged into the egr plug....

exhaust seems noticably warmer on the driverside when feeling at the tips

This car has set for 2 years being only started and let warm up a few times

now when this was converted to maf and I didnt get the plug all the way into the firewall and after spraying out the engine bay water filled up into a square ecc relay near the cpu it was hanging out just below the heatercore shroud area by the pass kick panel and was full of water and I had to replace it to get the car to run after the head install....

Need someone to help me figure this out...

gonna ground out pin 30 on the ecc and do the koer test today.....


and I have read posts for two weeks trying to find a cure, it seems the ones that have had this problem fail to post up what they have done to cure the problem.....

 

[jrichker]

The code numbers don't match with the computer type. The A9L computer only uses two digit codes.

 

[FrankenStang]

Moved to Tech.

 

[88foxvert]

The code numbers don't match with the computer type. The A9L computer only uses two digit codes.

indeed you are correct , I've been so frustrated I didn't even catch it .....it was purchased as a a9l there are no stickers on the eec anywhere...so I assumed it was an A9l since I hadn't had any issues until now , I hadn't read the codes....

also I ohm'd out the injectors all at 14.9

seems I have a drain on my battery somewhere too. Drove around a bit yesterday stopped a half dozen times never even acted like it wasn't going to start but this morning it was dead..... nothing left on I'm puzzled

codes in stored memory after the 10 seperator....172, 176, 452, 542

koeo codes.. 522,552, 565, 558, 542 which haven't changed


still have to ground pin 30 for the koer tests....

 

[jrichker]

I would clear up any questions about the computer being the correct one before proceeding. You could have a mismatch between the MAF and the computer as well as a computer designed to run something other than 19 lb injectiors. Couple that with the aftermarket MAF and you have a large pile of unknowns.

Troubleshooting battery drains:

Typically it is something draining the battery. Small things like glove box or courtesy lights are often the culprits. If you have an aftermarket stereo or alarm system, it is also suspect.

The ideal method is to disconnect the negative terminal, and connect a Digital Multimeter (DVM) between the negative terminal on the battery and the negative cable. Set the DVM on a low current scale of 2-5 amps if it doesn't auto range. Watch the current draw, and then start pulling out fuses. When you see a sudden drop in the current, that circuit is the likely culprit. Note that the computer, radio & clock will draw less than 1/10 amp to keep the settings alive.

See http://assets.fluke.com/appnotes/automotive/beatbook.pdf. You will need the Adobe Acrobat viewer which is also a free download – Adobe - Adobe Reader Download - All versions

 

[88foxvert]

I would clear up any questions about the computer being the correct one before proceeding. You could have a mismatch between the MAF and the computer as well as a computer designed to run something other than 19 lb injectiors. Couple that with the aftermarket MAF and you have a large pile of unknowns.

are there any indicators internally that will tell which cpu it is?? there are no stickers on the outside...

and I had this set up running fine with a fmu and powerdyne bd11a on a complete stock set up except for the maf conversion and maf & injectors would pull to 6250 until I lifted the heads blowing boost into the radiator only....tore it down installed the fresh gt40p's and other stuff.... blower has the belt off now because it makes the problem worse ......

 

[jrichker]

Without a dump of the computer rom or rom checksum, there isn't a simple way to find out what you have. With that information, you could match the rom contents against a known computer. Maybe some of the Tweecer guys can help out.

 

[88foxvert]

yeah I figured there would be nothing obviousin the ecc...... oh and the wife says it smells badly of fuel when shes driving behind me burn your eyes she says...I'll check out the current draw tommorrow and no aftermarket sterio or alarm ,but its not the courtesy light and not the glove box,hood or trunk as I have the bulbs removed to replace them.. also going to put a jumper on my neutral safety switch and run koer test and cylinder balance test tommorrow ....

 

[88foxvert]

Alright installed a known good a9l drove it around for 10 mins or so ....still doing the same thing pretty much except now it wants to die after it starts bucking. ...here are the codes I am getting...

67- neutral switch circuit open

81- secondary air diverter circuit failure

82- secondary air bypass failure

85- canp circuit failure

84- egr control solinoid failure

smog and emmissisions stuff is deleted.....


cm- codes

29- Insuf. input from vss

33- egr valve opening not detected



hopefully sometime today I can run the koer tests....

fuel pressure is at 40 psi when this happens and after dies it drops to 32ish and as soon as the engine comes back on its up to 40psi agian fuel pump is a 255 walbro with less than 200 miles ..... keep in mind it idles at 850 nice and steady and runs seemingly fine until 2500-3000 rpms.....

 

[88foxvert]

codes for today....


koeo 67,81,81,85,84

cm- 14, 29, 33, 41, 91

 

[88foxvert]

ok after putting a jumper on the neutral switch and running the koeo and cm test it will not run the koer test the cel light flickers and the engines dies............and I even said please
need some help here I cant seem to figure it out...........

 

[88foxvert]

had to jump pin 30 to pin 46

koer codes- 41, 91,33

cylinder balance test- 90-90-90

 

[allballsmustang]

it sounds to me like theres something going on with the ignition related components, atleast from my experience. Even though you have replaced the tfi module, have you had it tested? I just bought one the other day from the store and it was bad right out of the box... just a thought... hope it may help

 

[88foxvert]

yeah they tested it before I left the store and I have had a known good dizzy in there too same results would bad o2 sensors cause this?

 

[Black1987Stang]

sounds ignition related, open the hood up at night with the engine running and look at all the plug wires for them arcing off anything metal, youll see little blue sparks......also if you have a msd 6al take out the rev limiter chip....my friends was cutting out at 4,000rpm (6,000 pill) and once we took it out it was fine. but I'm betting on ignition related...

 

[88foxvert]

sounds ignition related, open the hood up at night with the engine running and look at all the plug wires for them arcing off anything metal, youll see little blue sparks......also if you have a msd 6al take out the rev limiter chip....my friends was cutting out at 4,000rpm (6,000 pill) and once we took it out it was fine. but I'm betting on ignition related...

just drove it to get o2 sensors and if ya granny it around 2500 or below its seems ok ,get on it and it spits and sputters almost dies check engine light flickers on and off get out of the gas clutch in to rev it cel lights gone.......
no msd stuff hooked up except the streetfire coil, koer has codes 41,91 ,33 sprayed the whole engine down with carb cleaner while running and got no changes ,18in of vacumme while at idle fuel pressure seems to stay at 39-40psi,
car has about 80k on it ...waiting for dark to check for spark leak....

 

[allballsmustang]

does it only do it in closed loop?

 

[Black1987Stang]

2 things I forgot to put in my last thread was....at WOT the computer doesn't use the o2 sensors for fuel management, it uses the fuel tables in the computer or through a chip. so I would rule out the o2's....and you said "it has 17 in at Idle and 22-24 when accelerating"
I can't see how it has 22-24 while accelerating, I could only possibly get that high if I'm decelerating.....I don't think it's possible to have more than idle vacuum when the throttle plate is open compared to it being closed at idle

 

[88foxvert]

mabey I should say then....... as you rev it it goes to zero close the throttle and it goes to 22-24" then settles at idle to 18"

and I figure it has the original o2's so they need changed anyway's...besides if they are bad wouldn't it make the fuel tables incorrect?/

I'm leaning towards a new fuel pump .......reason being with the stock fpr with vacumme attached it does not drop down to the 32-35 range it stays 39-40 psi and when driving tonight I actually watched the gauge and when it started bucking and spitting the pressure dropped to 20psi for a sec then back up to 39-40 psi and it doesn't increase with rpm just stays at 39-40 psi......

 

[Black1987Stang]

mabey I should say then....... as you rev it it goes to zero close the throttle and it goes to 22-24" then settles at idle to 18"

and I figure it has the original o2's so they need changed anyway's...besides if they are bad wouldn't it make the fuel tables incorrect?/

I'm leaning towards a new fuel pump .......reason being with the stock fpr with vacumme attached it does not drop down to the 32-35 range it stays 39-40 psi and when driving tonight I actually watched the gauge and when it started bucking and spitting the pressure dropped to 20psi for a sec then back up to 39-40 psi and it doesn't increase with rpm just stays at 39-40 psi......

k so the vacuum part is normal

the 02's do affect the ltft (long term fuel trim) which overtime updates the fuel tables to adapt to your engine....but if you just changed the computers and assuming you disconnected your battery when you did that I don't think it would have enough time to affect the WOT tables that bad....

the part you're talking about with the fuel pressure is kinda sounding like a clogged fuel filter.....when you go WOT (big need for fuel) it bugs out but if you go slow and easy its ok......