98 Camero with long tubes - will a tune fix this?

[snwboarder48]

Hey guys I need some help, not my car but my cousins car. Car idles fine, but when it comes up to temp, starts bogging and backfiring. LTFT are adding a ton of fuel across the board. Ive been playing with hptuners on my LS swap and know enough about LS engines and tuning to be dangerous, but not enough to diagnose someone else's build. I think I've ruled out anything mechanical, o2 sensors are new and there are no leaks on the intake or exhaust (as far as i can tell), car is only throwing a code for the EGR valve. All sensors appear to be reading and to the best of my knowledge are functioning properly. Im not a pro and dont want to take on tuning someone else's vehicle so the final question is: will a tune fix these issues or is there something else going on here? I dont want him to pay for a tune and have that not solve the problem. Apparently the car drove fine before the headers, but I never saw it. Also, to my knowledge, the tune file should be stock, but it is a used 98 camero.. . . . .seems to me that it should be throwing some other codes if it were truly stock. If a tune will fix it, any recommendations for a mail order tune?

Vehicle:
98 Camero 5.7 Manual Transmission

Mods:
Cold air intake
340 lpm fuel pump
long tube headers
high flow cats
egr delete

Tune File and logs:
Camero.hptCamero.hplCamero run 2.hpl

[abc]

Double check the exhaust is sealed up then it looks like a tune can fix it.

Did the MAFs get moved with the CAI? Do you have the tools to check fuel psi. while you are driving it?

I would put it in SD and tune the VE table first based on fuel trims then go back to tune the MAF if you want to keep it.

[snwboarder48]

Mass airflow sensor appears to be in the stock location. I can take a closer look at the exhaust manifolds on the heads, but looking underneath the welds are good and I can?t see any leaks there.

[MarcWolfe]

IAT 54c, 129F... If it's cold where you are, that can make it lean, by a lot.

[snwboarder48]

We?ve had some cooler days here in phoenix, but not relative to the rest of the world.

[bk2life]

Weve had some cooler days here in phoenix,.

not sure where youre at in phx, but in this phx its pretty cold....

phx.jpg

[MarcWolfe]

"cold air intake", 129F intake, I don't think any sane person would call over 100F a cooler day.
Sounds like you need to fix/replace a sensor/wire.

[snwboarder48]

This car is not in pristine condition, it?s been well loved haha. I?ll take a closer look at that.

[twenglish1]

If it is not blocked off from the engine bay it is a "Hot air intake" and it would have been more beneficial to keep the factory intake ducting, where the air is drawn in from outside the engine bay

[SiriusC1024]

IAT isn't going to throw off fueling. What do you think the IAT sensor is for?

It's adding 40% fuel. If stock engine then restore stock O2 settings. Increase CL enable temp for longtubes so O2's are warmed up. (attached)

This problem has more to do with a 340lph pump behind a reg that'll only support 255. Pump probably got damaged. Check fuel pressure.

[Alvin]

I'd verify fuel pressure as well.

Also, MAF seems to be reading a touch lower than it should especially at idle. I'd clean the MAF. That can move fuel trims by 15-20%. Check again for any airleaks behind the MAF. The rubber elbows on the PCV for those often rot out.

Headers alone shouldn't have changed all this that much. The popping you describe is not going to be a tune issue but likely a cracked spark plug or burnt wire. both of which happen often with new header installs.

[snwboarder48]

If it is not blocked off from the engine bay it is a "Hot air intake" and it would have been more beneficial to keep the factory intake ducting, where the air is drawn in from outside the engine bay

I agree, unfortunately car has been around the block a few times and came this way. Have to live with it for now.

[snwboarder48]

IAT isn't going to throw off fueling. What do you think the IAT sensor is for?

It's adding 40% fuel. If stock engine then restore stock O2 settings. Increase CL enable temp for longtubes so O2's are warmed up. (attached)

This problem has more to do with a 340lph pump behind a reg that'll only support 255. Pump probably got damaged. Check fuel pressure.

Can definitely take a look at that. Pump was ?upgraded? when the factory one went out. Will try to verify fuel pressure.

[snwboarder48]

I'd verify fuel pressure as well.

Also, MAF seems to be reading a touch lower than it should especially at idle. I'd clean the MAF. That can move fuel trims by 15-20%. Check again for any airleaks behind the MAF. The rubber elbows on the PCV for those often rot out.

Headers alone shouldn't have changed all this that much. The popping you describe is not going to be a tune issue but likely a cracked spark plug or burnt wire. both of which happen often with new header installs.

This has been my thought as well, headers on a relatively stock motor shouldn?t require a tune right? I?ll check that out as well. Appreciate all the insight guys, really do. I?ll report back with findings, busy week at work, so not sure when I?ll be able to get back out there and help him out, but I will keep you posted!!!

[snwboarder48]

Just wanted to report a k, good tip on checking out the fuel pump! Not enough capacity in the stock regulator and fuel was boiling in the pump causing a drop in pressure! Replaced with stock unit and works great.