numskull

Hey all, Ive been driving my car alittle since I put a tag on it. At WOT is unreal....Lets just say I thought I was going into the ditch when I hit 5th....nice set of pos....But after its warmed up and ran for a bit, it will go dead at a stop sign, and then it acts like the timing is high or low during the cranking(turning over stop turn over stop) If ya know what I mean but it will fire up.

So I was thinking, If this car set for over a year with no battery will the PCM lose its tune? Kinda like a destop if the mobo battery goes dead?

ACE1252

The 1994 and up PCM tunes are stored on an EEPROM that should be okay not powered for at least 10 years straight. As long as it gets power at least once every 10 years, it should be fine.

sbs

With no battery it will forget the BLMs.

But that isn't your problem.

mrmint69

The computer relearns very fast and will take just seconds to minutes.

numskull

Actually my BLM is off, one side is at 107 and the other is at 137 in closed loop. Should I try and adjust?

I have lt1 edit....Ive never adjusted anything though....I dont know where to adjust either.....lol

Kevin Blown 95 TA

You may have an air leak somewhere causing that. Maybe check your exhaust gaskets.

numskull

I was just doing that...lol. But I have my fuel pressure was set to 30., if I adjust it to 43 it doesnt run.....just the smell of raw gas. I have changed every sensor except o2's

It was professionally tuned when the engine was build...but something has went wrong. The only ses light is map sensor low... i believe.

I was gonna take it to a speed shop, but their crazy on thei dyno and tuning prices...so Im stuck trial and error.

mrmint69

A normal running lt1 engine with the fuel pressure set at 30 will lean out at higher rpm's. Does it have a "professional" tune in there right now? I would drive very little until you figure out the fuel pressure problem. Unless you know what your doing, making changes in the tune will most likely mess things up worse. What do your O2's show when running a datalog? Are they changing rapidly from 0xx to 9xx? It should be all over the place and look almost random unless going wot, than you will be in the 9xx the entire time.

2QUIK6

Fuel pressure should be set or checked with the vac tube unplugged from the regulator. Not clear if that is what you did. Should be in the 40-43 range. Would not be the cause of the out of balance blms. Bad o2 could be the cause if you are certain there are no exhaust leaks before the o2 sensor. Or maybe a stuck injector on that bank.
If your scanner shows the O2 cross-counts they should cycle from 0-255 in less than 90 seconds for a healthy o2.

numskull

First thing, thanks for your help everyone!!

injectors have been freshly tested and cleaned.
O2sensors cycle from 250-500 range. one is always higher.
engine floods non stop. idle and wot. When I nail it my wife says its smoke gas smoke and she can smell gas. but it doesnt sputter, lag at wot. runs like a beast. but at cruising it sputters alittle from loading up. I have never messed with the tune. I reinstalled the engine when i bought it and thats the way it ran. guy i bought it from said he never messed with it either but did notice it flooded alittle at idle, now it worse he said.

i have a copy of the tune when it was dyno tuned...should I just reload it in?

Whats a tell tell sign the o2 sensor or sensors are bad?

ACE1252

What is the three letter extension on your tune file? Is it .bin? If it is .bin, I would like to have a look at it.

Something has to be really wrong somewhere if you have to turn down the fuel pressure 13 psi to run half decent.

Have you done anything with the MAP sensor(to fix the code)?

Are you still running Accel 36# injectors?

Have you done any voltage checks of the throttle position sensor?

As a couple others have stated, I don't think that reloading the tune is going to help the problem.

numskull

My fuel pressure was set there when I got the car. I have the datamaster logs, open and closed loop. and I have the lt1 edit file also.
Oh, yes i still have the Accel #36 injectors.

whats crazy, is that my buddys mustang runs mid 11's all day, and last friday we played and the camaro still screams and i still took him easily....i just wonder how much better it would run if i get it running good.

If you can look at my file, i woukd be glad to send them to ya. Thanks!!

mrmint69

You can upload your datalog to a free site and put the link on here. I just checked my old one and my O2's reading is like this. 209 169 769 639 235 244 817 289 209 830 as an example of proper working sensors. You want a wide variety of numbers and if your staying under 500 all the time you might have bad O2's. You want to check the sensors after the car is warmed up and I usually go for a quick drive under different conditions. Just don't go out and ruin what sounds like a very nice engine, running it hard with your current issues. Not sure who tuned it, but if you keep having trouble, you could get a mail order tune and see if that helps once you get the bugs worked out. Fuel pressure is the most important. Do you know how much HP you have? The adjustable fpr might not be such a good idea and be causing some of your issues, but you state you possibly have a 10 second car and that changes things.

Injuneer

There's already been a thread regarding the engine "running rich", the low fuel pressure, the questionable injector sizes, etc. I spent quite a bit of time looking at data logs. Looks like we're going back to step 1.

https://www.camaroz28.com/forums/lt1...-853979/page2/

If the O2 voltage stays in the range of 250-500mV, its indicating the exhaust is on the lean side. That would cause the BLM's to elevate, but you indicate you have a "107" (lower limit stock programming is 108", and its running rich.

Do you see the contradictions here?

numskull

One side does drop to 107 but rebounds to around 117. SLterm run around 130. in open loop the slterm is at 128 and the Lterm is 137 and 153, isnt that too high even for a cold engine?
Actually One side is at 117, the other is at 157 range in closed loop. unbalanced, and i believe you said it was a common issue with large throttle bodies. since one side is lean. Ive wnet thru everything for a vaccum leak,replace the sensors( except the o2s) had the injectors cleaned, replace plugs wires ect, Im just out of ideas, and it act as if the timing is off when its warmed up during cranking, doesnt turn over smoothly.......Thats why I was wondering about the tune.


And the other is rich. Im gonna do a bench test on my o2 today. Actually the O2 sensors go from 200-702 range




Injuneer, What would you do if your car was acting like this?


mrmint69, theres rumors that the car ran 10's before I go it, but I cant say 100% cause I havent ran it yet, I bought it with the engine oil pump screen fell out, lucky for my he was at a stop sign when it happened and he noticed it and towed it home..lol, so I pulled the oil pan and took pic and replaced the oil pump and screen. Engine still looked new.