Hairy W Bush

I am posting in this section for more in dept evaluation. previous thread with some of my responses to questions you might havehttps://www.corvetteforum.com/forums...ing-again.html
It used to stumble after a couple mins and clear up, and then was actually gone for a while. Now the car wants to die when it warms up right when it hits 180. pushing the ac on will practically kill it. I have already replaced the passenger side 02 sensor for a code when this was not happening. I have to restart it every time I drive it now to fix it. My mpg has dropped again, from 27-28 highway to 24. No CEL ever and I am sure I do not have a vacuum leak.
http://www.filedropper.com/stallornot
it actually hasn't stumbled in a couple weeks now, but my mpg is still low and this is what I noticed during my drive when i scanned this several weeks ago. I was looking at my Factory service manual and there's a page for tech data with all the normal values. if you guys take a look at my Datamaster file, you will notice the 'Fuel Trim Cell' average is extremely low. 16-18 is what the book says and what I recorded was a fraction of that.
there no 'Inj. Pulse width' section on the scanner so I assume 'INJ DC' is the cell. Well, when the fuel trim value is normal, so is this (1-4) and when it gets low, the inj dc values double.
What would be the issue there? new map sensor, iac valve, fuel regulator, tps, right 02 sensor, cleaned maf, cleaned air filters (as of today),

FrankieD

I reviewed your Datalog and I notice that your LTERM Counts are both sitting at 145/145, This is on the lean side for AFR( Air/Fuel Ratio) There is no change throughout the Datalog. In my opinion this is a fuel delivery issue. Start with changing the fuel filter and take a close look at your Fuel injectors. If they are original consider at minimum getting them professionally cleaned, But the better choice would be to replace them. There are much better Fuel Injectors now days than the Factory issued ones. Keep us posted on your results.

Hairy W Bush

Ok I don't know if the injectors are original or not. they are red. I did go out there and ohm test them while the car was off and they tested ok but i don't know if that has anything to do with how clean they are.

Hairy W Bush

I changed out the filter today and just cut up the old one. It wasn't dirty at all and my usual warmup stumble is still there.

FrankieD

Seeing that your datalog is indicating that your LTERM Counts are both sitting at 145/145, means you are not getting any Fuel Trim correction in Closed Loop. I would start by going back to basics and remove your Granatelli MAF for a stock one. Once , you have put on the stock MAF, take another datalog and we can see what that shows.

Hairy W Bush

I don't have the stock one so that would require me to purchase one. I even called Granatelli one time about this issue and they wanted like $75 to test it. Also there is a tune on this car so I believe going backwards would just cause another issue.

FrankieD

There is something just not right with your LTERM sitting both at 145/145 during closed Loop. The LTERM's should show some signs of Fuel correction at some point . Who did the tune? Do you have a copy of the tune? Perhaps we can take a look at it to see if it provides any clues

Hairy W Bush

I'm at a loss as well. I don't have a copy but I do have the name of the place that did it. Do you want the name?

FrankieD

For reference it would be nice to know who the Tuner is. Can you provide another datalog that starts right from when you start the car on Cold startup and carry it through some driving time as well? Do not turn on the AC during this datalog.

Hairy W Bush

Apparently from an info sheet I have on the car it was done by 'Mad Tuner', but the dyno sheet says Powerhouse Racing and Performance http://www.powerhouserp.com/

Cliff Harris

I think you have a vacuum leak. That is the most common cause of stumble and your high BLM also indicates a lean condition.

Hairy W Bush

If it is I can't find it. I think I've looked at and tested just about everything.

Hairy W Bush

Here is the scan from a drive to a store just a few minutes from my house. http://www.filedropper.com/startupstumble

MrWillys

Your ecm is telling you that you have a lean condition. Did you change injectors recently? If they are good you need to change the flowrate in your programming. This is how lean you really are:

128 divided by 145 times 24 (assuming the 95 is 24) = 21.2 lb.

Either your injectors are bad, or the ones you bought aren't as claimed. I get this a lot where a guy tells me he has 24 lb injectors and it turns out they flow 20. We must also think a fault in the fuel delivery system to.

Hairy W Bush

I know nothing about the injectors other than the color. All this work was done by the previous owners. Why would the tuner let it be like that??

FrankieD

Do you have an Adjustable Fuel Pressure Regulator?
If you do crank up the Fuel pressure to 60PSI and then make another datalog. This will give us some insight if your injectors are under rated.

Hairy W Bush

No it's just an oem replacement

MrWillys

Can you give us a picture, and or number off said injector?

aDigitalPhantom

A big thing to remember when buying in injectors, and dealing with others that bought injectors is what fuel pressure rating are the injectors rated for. Many people don't realize that you need to know the fuel pressure the injectors are rated for.

If you bought 24lb/hr injectors for 58 psi they would be 21.2lb/hr@45psi

Hairy W Bush

0280155759 red color