Stumble with 50 lbs Inj.

[NTMD8ER]

Here's my problem:
It started out as an O2 code 44 lean, problem so I swapped in a good Heated used o2 from last year. Then it all went south from there. that did not fix the problem so I put the original back in. then the car starts to stumble and snort from a dead stop with minimal throttle till about 1000 rpm's then fine. Since then these Items where replaced or checked

O2 replaced with Single wire AC delco New
Driver side header crack fixed
Maf sensor changed
reset AIC
Adjusted TPS
Checked and reset cam Sensor
replaced computer
changed chip to Idle at 1100 rpm's
replaced spark plug wires
replaced coil pack

Now the stumble show's up every now and then, car seems slow and heavy from a start. After the car is moving she's good and strong. so I started playing with some of the chips I have.

I put in My stock injector streat chips and car runs perfect but I can not build boost over 12 pounds before getting High knock

I am now lost why would it run fine with the stock injector chips and not the 50# chips. Car ran fine until the 02 lean problem
had no problems with chips before. 50# chips are Jim Testa street and 110 race. Stock chips are Red Armstrong and Thrasher.
could the injectors have gone south, I'm thinking of putting the stock injectors back in.


thanks in advance for the help.
Brad

 

[charlloots]

did you adjust your fuel pressure
do you have a ajustable fuel regulator?if yes
maybe the tranny or convertor needs an upgrade

 

[NTMD8ER]

I have adjusted the fuel pressure form 45 line off to 40 up to 48 and back to 45 with no effect on problem.

thanks
brad

 

[T-Type Mike]

I had the same problem persisting for over a year. Same scenario. I went through everything. Car ran like crap. I used my 110 race chip and all is well. My problem turned out to be in the chip program.

 

[GN ERGY]

E mail Tim Testa, you have 2 of his chips, he should help you out. He knows his stuff.
Tarey D.

 

[NTMD8ER]

Seems like the concences is the chip's. that is what I thought when I put the stock chip back in and everything was fine. but then I started thinking why would 2 chips that where fine start giving me trouble. I'll contact Jim and see what he say's.

Thanks for the replies.
Brad

 

[tcgn]

I have a series of problems when I install msd 50`s and 50# chip.
After a half a year of chip fine tuning.I had the injectors flow tested and found out they are approx. 43# injectors.So I changed my injector constant table to 43# and solved my problems. The numbers on the injectors are 50# but it is really a 43# on the flow test.(VERY DISAPPOINTED- Called Ramcharger`s
and told Kevin about it and he never called me back with any explaination).I`ve never called them back.

 

[forzfed]

I believe the flow numbers are at 85% duty cycle or somewhere around there. Mine came out to about 43.5. Stevie Y's chip works great, no stumbles.

 

[TurboJim]

WHat is the BLM value when its stumbling?

I cant see how one day the chip just crapped the bed....both of them no less....

Oh, and if you edited MY chip, make sure you reset the tamper, or you may be running in limp home mode.

 

[TurboJim]

Originally posted by tcgn
I have a series of problems when I install msd 50`s and 50# chip.
After a half a year of chip fine tuning.I had the injectors flow tested and found out they are approx. 43# injectors.So I changed my injector constant table to 43# and solved my problems. The numbers on the injectors are 50# but it is really a 43# on the flow test.(VERY DISAPPOINTED- Called Ramcharger`s
and told Kevin about it and he never called me back with any explaination).I`ve never called them back.

Thats about right if you had say PTE flow them. That would be 45psi at 90% DC @ 6000RPM. At 100% DC theyre 50's. I asked why they rated them like that, and to be honest, I forget the answer

 

[NTMD8ER]

Today I put Jim's chip back in took out the 1100 rpm chip. This is what the car acted like. If I eased into the throttle it would stumble, but if I just flored it, it was fine. the scanmaster readings are below. Car was at operating temp drove it around for about 30 min. when I get over 1000 rpms it fine, could this be a bad TPS? Jim we didn't change any thing on your chips. I really don't think its the chip since the 110 chip was not in when this started. I was thinking that maybe the programing in the 50 lbs chips and the stock chips might point to the problem. Car is slow to spool even after it gets over 1000 rpm's but spools fine with the stock inj. chips.

IDLE
af 05
LB 40
BAt 13.4
INT 130
BL 150
CLE 167
ATS 130
TPS .42
IAC 22
CC 0-250

Stumbling
af 16
LB 124
BAt 13.4
INT 118
BL 128
CLE 170
ATS 130
TPS .42-1.36
IAC 49-101
CC 0-250

65 MPH
af 34
LB 71
BAt 13.4
INT 135
BL 150
CLE 164
ATS 86
TPS 1.98
IAC 80
CC 0-250


Thanks the replies
Brad

 

[TurboJim]

Have you reset the ECM since the O2 died? If the O2 goes low, it sends BLM high. Otherwise, What is your fuel pressure? Do you notice your BLM values when its NOT stumbling is 150? Whats happening is you're going from a cell adding fuel, to a cell NOT adding fuel. Once that cell learns to add enough fuel, the stumble will more than likely be gone. OR, raise your fuel pressure (if its not high already) I'd guess 4-5psi. Get that BLM grids back to normal. If the fuel pressure IS already high, you'll need to find out what us causing the high BLM's. Possible a bad MAF or post MAF air leak. Once you find the cause of that BLM, my bet is the car will run fine once again.

 

[NTMD8ER]

The computer has been reset several times. I have the fuel pressure set at 45 line off, so your saying to raise the pressure
4-5 more lbs. I'll try that and try and get another maf, My second Maf was used so it could be bad but it is beleived to be good. I'll be out of town for the next 2 weeks, I'll work on it more when I get back

Thanks for the help.
Brad

 

[TurboJim]

Originally posted by NTMD8ER
The computer has been reset several times. I have the fuel pressure set at 45 line off, so your saying to raise the pressure
4-5 more lbs. I'll try that and try and get another maf, My second Maf was used so it could be bad but it is beleived to be good. I'll be out of town for the next 2 weeks, I'll work on it more when I get back

Thanks for the help.
Brad

Nah, your FP is high enuf. I suspect a MAF or post MAF leak. Or any other reason for BLM to go high. You change to a non AC PCV valve by chance?

 

[tcgn]

I flowed them myself with my machine @ 43 psi,energizing the injectors at 100% duty cycle and maintaining the pressure at 43# psi while being energized.Battery volts approx. at 14 volts.Test is performed for 1 minute and it flowed 15.5 oz. using 6 lbs. fuel per gallon calculated to 43.5#.I did this test 3 times just to confirm my
disbelief.

 

[TurboJim]

Wonder if theyre Delphi 42's and not 50's

 

[NTMD8ER]

We'll I took the fuel pressure up to 50 psi, stumble pretty much went away and the car became very responsive, I'll recheck the the hoses and clamps when I get back from Alaska. I do remember when I changed the O2 Sensor the first time I checked the fuel pressure and it was up to 49 psi I backed it down to 45 and that is when this problem started. For a second I thought maybe the pressure gage was bad but now my o2's are up to 860 at fuel throttle. I should have a new Maf when I get back, I'll try that and see what happens.

thanks
Brad

 

[NTMD8ER]

The receipt says MSD 50's they were purchased from PT&E.

Is there any markings on them that will state what they are.

 

[TurboJim]

Maybe yer gauge isnt accurate?

 

[Dan K]

Originally posted by NTMD8ER
The receipt says MSD 50's they were purchased from PT&E.

Is there any markings on them that will state what they are.

There should be some numbers on them. I found these on mine...17113738 and 3282.
What do yours have?
Or anyone with MSD 50's....what do yours have?