jeromio

Are you sick of me yet? So, my car is now running and I actually drove it!! But, as soon as it gets to 190 degrees, it starts to idle really crappy. It's easy to kill it - it stumbles real bad.

Since everything else has been stupid shibbit (fouled plugs, air in the water passages), I'm hoping someone can chime in with another obvious fix before I drop $200 on EFILive and risk a divorce.

Oh yeah, I alos ran it out of fuel. It had 5 gallons in it, but I had a vent line uncapped - so I guess it evaporated? Anyway, I would suspeect grunge, but the tank was completely cleaned out before install - and it's a new (99) plastic camaro tank.

Also, I assume that the 4 O2 sensors are all the same. I have the 4 from the donor, and I just grabbed 2 and put one in each manifold. They both heat up when the ign. switch is on. Not sure what other tricks there are to verify that they are good. The motor goes to closed loop mode when hot, yes? So, I dunno. It idles beautifully, and then when it gets to that magic temp, it's like someone threw a switch and it starts to run like crap.

BTW - [b]Holy CRAP is this thing fast![b]

Pro Stock John

iTrader: (34)

Congrats.

Perhaps your coolant temp sensor is messed up and once the car warms it it runs rich as a protective measure.

jeromio

I think the temp sender is ok - the reading I get from atap is the same as I get from the autometer gauge.

I'm thinking maybe the O2 sensors are hosed? I have another pair that I can try.

I'm starting to wonder if EFI Live wouldn't be worth the money - less time wasted head scratching and guessing.

Speartech

iTrader: (14)

If you think the O2 sensors may be part of the problem, simply unplug them! You will remain operating out of the open loop tables is all, so there won't be any fuel correction. Other than setting a code for the open sensors, the engine should run fine and it's a quick and easy test to help determine the problem.

jeromio

Really? I'll try that then.Thanks for the tip.

I was playin around with the trial version of EFI Live - only lets you run it for 5 seconds at a time. Very powerful sales tool - it's really cool seeing all the graphs and such. Anyway, O2 B1 and B2 seem to vary quite a bit. They'll both track pretty closely and then there'll be a hiccup in the reading from B2 - either up or down by between 20 and 60%. That doesn't seem right.

BUT, I think I may have an exhaust leak on the passenger side. Need to check that out. B2 is pass. side, yes?

jeromio

Okay. SO, I did have an exhaust leak on the pass. side. The gasket blew out. I fixed that and also swapped out another O2 sensor (that one was black with soot, but appeared unclogged?)

BUT, I still have the exact same problem. If I disconnect both O2 sensors, it runs fine - maybe a tad rich by the smell-o-meter. I can't find my 4th sensor to swap with the driver's side.

Should I buy a new sensor ($$)? Those dollars would eat into my EFILive fund....

Speartech

iTrader: (14)

You don't have the right and left sides swapped on your harness do you? They go bonkers when you try to correct the left side fueling with right side feedback!!

jeromio

Nope. I've never even removed the harness from the motor.

I have yet to pull the driver's side sensor - prolly coked up like the other one.

LS-1st-Gen

Ever figure out what was wrong? Still sounds alot like my problems. Runs fine up to 180 or so, then idles like crap until the fans switch on, at which point the idle smooths out. I have no clue what the deal is.

-Gordon

jeromio

I dunno. This thing is like a Jekyl/Hyde. I re-did the idle learn proc. about a month ago and everything seemed to have cleared up. Then it sat for 3-4 weeks and the hot idle went to crap again.

Then I drove it to the beach - about 3.5 hours. When I got off the freeway, I noticed the idle was nice again - although it was running rich and smoking a bit. Arrived, parked, got back in an hour later and the hot idle was crap again!!?!?

Just got back, again, off the high way after 3 or so hours of sustained 85mph and the idle is lovely. I'm guessing it'll go to hell again though. I need to get EFIlive and log this wierdness.

LS-1st-Gen

Let me know how it turns out

60Chevy

Use a scan tool to watch your coolant temps. I suspect you have an air pocket that causes the computer to go into a fail safe mode. Air pockets can reach upwards of 400 deg F under pressure and heat. During a highway cruise, the water pump is flowing a lot of water through the system giving the computer an accurate temp signal. As soon as the car sits or idles for a long time, the coolant flow is low and the air pocket returns to around the sensor location. When the processor sees an overheating situation the result is usually to turn both fans on, dump in a lot of fuel (smoke out the tail pipe) and retard spark for power reduction (rough idle). The trick is to actually look at the data stream coming from the processor and see what the processor is seeing. **** into the computer is **** out of the computer. The air temp sensor can do the same thing but that sensor has to tell the computer that the air is really, really hot (over 200 deg F). That is my idea. Hope that helps you out.

LS-1st-Gen

How do I vent the air from the system? My cooling system consists of the original 67 radiator with the throttle body coolant line hooked up to the auto trans cooling tank, which Ive opened up to the rest of the system. I thought it might have something to do with this.

-Gordon

jeromio

I actually did have an air pocket in the head(s) when I first cranked up the motor. Took ahile to work itself out.

I'm fairly certain (90% ?) that I don't have any pockets. My ATAP temp reading matches my gauge reading. The motor does run slightly hot - about 195. And it gets up to 210 or so if I sit at a light on a hot day. I have some fan issues - fan doesn't come on until 195 and it doesn't stay on long.

When I say my idle is rough, I guess I'm not being very clear. It actually sort of drones up and down, will cough and sputter and the motor will occasionally even die. In order to even it out manually, I really have to work the throttle. It's really not so much a rogh idle as it is a state of about to die-edness.

Pro Stock John

iTrader: (34)

You need to buy a scanner or scanning software, or locate someone local to borrow theirs.

I suspect that you have a bad coolant temp sensor in the cylinder head, or a bad IAT.

IAT, well you could get a resistor and put it in that, and see if that helps.

You can bleed the cooling system and get rid of air.

Speartech

iTrader: (14)

"...fan doesn't come on until 195...."
Huh? It's an engine not a refrigerator! When do you think a cooling fan should come on?

I'd sure like to get my Tech 2 on your setup; I think we could straighten it out quick. I don't remember, does your engine have an aftermarket cam in it?

jeromio

I guess I'm just a bit worried that 195 is too hot for an operating temp.

I'm a bit far from Indiana unfortunately for me

My motos is all stock, except for EGR deletion. The IAT is brand new and seems to work well according to the ATAP readings. It's mounted about 3 inches ahead of the MAF which is mounted about 5 inches ahead of the TB. I only have the basic ATAP S/W so I can't see IAC.

The difference I saw between air pocket and what I believe to be no air pocket was pretty extreme. The motor would heat way up, run like total crap, etc. I kept venting the rad cap (have one with a lever on it), blowing out steam, shutting down the motor, adding collant, etc. At some point it needed like 2-3 quarts of coolant - my guess that the pocket/bubble finally passed. Anyway, that was loong ago. My coolant level has been very stable. I have a jicky reservoir that is transparent and it has stayed at the same level.

Motor runs great while driving and at WOT - although I don't really have anything to compare it to. I mean, it seems great to me. Got 22mpg on a recent highway trip. It just doesn't like to idle.

Pro Stock John

iTrader: (34)

Jeromio you need to look at some stuff:

1-iac counts
2-iat temp
3-coolant temp
4-misfires

Try and contact local f-body guys and meet up with someone, it's hard to tell over the web. Do you have a surging, rolling idle? What does it idle at?

jeromio

I hooked up ATAP this AM to clear codes (keep getting skip shift which is annoying).

So, I dunno why I never noticed that you can graph O2 readings with the basic version of ATAP. I did this and Sensor 1 (Bank 1 - bank2 ain't there) reads all over the place. Varies wildly from about 150 to 900 mV. It'll stay up at 800 or so for maybe 1-2 seconds at a time, but mostly it just draws big zigzags. Sensor 2 stays right at 450mV. Totally steady. It blurped down to 50 for one brief instant. I let the car idle for about 5 minutes. Gun the throttle and Sensor 1 will react, sensor 2 does nothing. It's not a totally straight line, but close.

So, which one is broken? Both? I'm thinking this is the source of my problems. These suckers are expensive too.

LS1 PWRD

Bank 2 is the culprit. The O2 sensors will bounce all over the place normally.