Well, After replacing a faulty injector, the mixture has leaned out a little, but is still running rich.
I don't have as much popping on decelleration anymore, but my autometer air/fuel ratio gague is reading just about 90' to the right; which is a pretty rich mixture.

In WinALDL, the O2 usually reads anywhere from .860 - .950. I have tried different PROMs, but the mixture was rich with all of them. When I bought the car, it had 13lbs of fuel pressure, and I have dropped it back down to 11.5 --- but the mixture did not change.

Anyone know how I can lean out my mixture?

The only abnormality with sensor readings, is the IAT reading. WinALDL reports the IAT reading anywhere from 180'F - 230'F. I've replaced the sensor, but it still reads these values.

How are you TBI guys controlling your mixture? Has anyone else noticed WinALDL reading really high on the IAT sensor?

Thanks,

Thomas.

------------------
1992 RS Camaro - Red
305-TBI/5 Speed Manual- 3.08 geared rear
1.6 Roller Rockers / Open Air K&N Filter / TBI Spacer / ADS Super Chip & custom burned Off-Road Only chip /
Headers - 3" Cat'Back - Flow Master - Adjustable Coni shocks & struts / 16" factory wheels

 

That's not a high IAT, really. About normal. You need to check your BLM's. Your O2 sensor will adjust the fuel to the correct amount. Sounds like your ECU might not be doing that for you which could mean LOTS of different things... like bad O2 sensor, bad thermo, bad coolant temp sensor, etc...

What is WinALDL telling yout he BLM's are?

 

Ok, I was thinking that the IAT (Intake Air Temperature, right?) would reflect the temp under the hood.
I have the IAT sensor relocated to the A/C receiver line. When I started the car up lask week, with outside temp being 30'F, the reading was still around 190'F.

The BLMs go anywhere from 108 at the low, up to 128. 128 is usually only at full throttle though.

I replaced the O2 sensor about 1-2 months ago because I suspected it was bad. It was throwing codes at me. No codes since it was replaced.

You mentioned coolant temp sensor ..... kinda funny you mentioned that, because the coolant guage in the cab stopped working 3 days ago. WinALDL still reports the correct coolant temp, so I figured the sending unit for the dash guage must be bad. Would this effect the mixture?

Thanks for the ideas,

Thomas.

 

BLM is usually locked to 128 at WOT so that is not "good" data. If you are at 108 BLM, you are still quite rich (15.6% rich or so) and I believe that most PROMS have the Minimum allowable BLM set to 108 so you could actually be much richer than that, ie, your actual BLM could be much lower than 108...

IAT problem???? How are the coolant temp readings? After an overnight cold-soak, the IAT and engine coolant temp readings should be rather close, not air temp above 100* if the air is 30*. You have the right numbers/caculations?

EDIT: I would remove the ADS Superchip and try the OEM PROM and see how the BLM's behave, too. But, if IAT is that high and you are sure about the data, something ain't right. Check the sensor with a ohmmeter, if yo uhave not already.

[This message has been edited by fast_broker (edited December 11, 2001).]

 

The coolant temp looks normal. I have a 190' stat in there, and the temp usually hovers right around there. If I'm stopped and idling, then it gets up to 210' or so, but the fan kicks on and brings it back down to 190' or so.

The only way I know how to check the IAT reading, is with WinALDL. I'm thinking the same thing you are; IAT shouldn't read so high when it's so cold outside. Is there another way to verify the IAT output?

I've run WinALDL a good 2 dozen times in the last month or so, and the IAT was never below 100'f. This is what made me replace it, thinking it was bad.

Any other ideas? Thanks for the info so far .......

Thomas.

 

.185k ohm= 210*
.45k ohm= 158*
1.8k ohm= 104*
3.4k ohm= 68*
5.7k ohm= 53*
7.5k ohm= 32*
13.5k ohm= 14*

Got (cut pasted) these numbers from the other "xxx IAT xxx" post on the TBI board below. Hope they are right, I HAVE NOT VERIFIED THEM. Ressistance values across the IAT for corresponding ambient sensor temperature. Ohmmeter should help you figure it out. Hopefully, you just have a bad sensor.

Coolant temp data you described is normal.

 

Great! That's exactly the info I need to verify the reading WinALDL is telling me. If the resistance confirms the 200+' in WinALDL, then I dunno what is happening.

I already replaced the IAT sensor, so maybe this would mean that I have an ECM problem? Or a short somewhere in the system?

I guess I'll just wait and see what the Ohm meter tells me.

Thanks again man,

Thomas.

 

i would suggest lowering the fuel pressure even further. the operating range on the injectors is from 9-12psi(according to factory specs) so you still have a lot of room left to lower it. you may also want to look at your timing a little. if there is not enough timing present the fuel will not all get burned off correctly and create a false rich reading.
start with a little lower fuel presure and see if you can put in a little more base timing with out gettign any knock. this should also help your throttle response an dfuel economy.

later
tim

------------------
91 Camaro RS-LO3,Auto
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If the fuel doesn't all burn or doesn't burn properly, you usually get a LEAN reading from an O2 sensor, not usually a RICH reading...


[This message has been edited by fast_broker (edited December 11, 2001).]

 

Hey Tim,

My timing was at a 4' advance since I bought it (~10 months ago), but I incresed it to 6' about 2 weeks ago. It definitely likes the 6' better than the 4', and no more knocks generated either.

Right now, I have the stock fuel regulator installed. The adjustable one I have will only allow a min setting of 13lbs. Should I do the 'Stock FPR mod'? Will it allow me to lower the fuel pressure below 11.5lbs?
and also, will there be any adverse side effects from lowering the pressure?

The only reason I want to lower it, is because I'm under the impression that a leaner mixture, will result in better performance; at least, that has always been my experience in the past ..... just never with a TBI setup.

Thomas.

 

If you have an essentially stock engine with an aftermarket chip, I, too, think you only need OEM fuel pressure, not 13psi

 

My MODS are in my sig. There's a few good improvements on the car, but nothing that touches the core engine.

Do you see anything in my sig that would make my car benifit from altering the fuel pressure?

------------------
1992 RS Camaro - Red
305-TBI/5 Speed Manual- 3.08 geared rear
1.6 Roller Rockers / Open Air K&N Filter / TBI Spacer / ADS Super Chip & custom burned Off-Road Only chip /
Headers - 3" Cat'Back - Flow Master - Adjustable Coni shocks & struts / 16" factory wheels

 

Not more than maybe 1/2 psi from OEM... BUT, the ADS chip may have been programmed to increase the fuel parameters so if you also added FP, you've got WAAAAY too much fuel. Hence, the rich condition indicated by your BLM.s


You haven't really increased the efficiency of your "pump" enough to warrant a fuel pressure AND a PROM change.

Diagnose/Check/fix the IAT before you do anything!!!


[This message has been edited by fast_broker (edited December 11, 2001).]

 

If the IAT is moving then it's probably correct. My underhood temp readings are usually really high as well. Usually right around the engine temp since I still have the hood weatherstripping on and it keeps the air from escapping.
BLMs at 108 means you're running dog rich according to your o2 sensor. Check your spark plugs to make sure you really are running dog rich. A bad o2 sensor can do stupid stuff like that. Definatly turn down the fuel pressure even more if your BLMs are at 108. If you cruise in 3rd (drive) gear at 4000rpm see what that BLM value is. If it's close to 128 then that's the closest you're going to get with your combo and not burning a custom eprom! It's okay to run rich in open loop but you are WAY off the scale with a 108 BLM. If you've been driving this like that for a while it wouldn't suprise me if you've washed your cylinder walls and have gas in the oil pan! This can be a very bad thing. Get your BLMs around 128 under slow moving throttle position! Like fastbroker pointed out, BLMs go to 128 instantly when you mash down the pedal.

 

I replaced the IAT sensor recently, so I'm pretty sure the sensor is working. I tested it by disconnecting it with WinALDL running, and the reading immediately went up to ~300'f.

I also replaced the O2 sensor about 1-2 months ago, so it shoul dalso be good. Could my air/fuel ratio guage be messing up the O2's readings?

The BLMs are not fixed at 108, that's just the lowest number I have seen it register. On the way in to work this morning, I hooked the laptop up for the ride. I have screenshots of the readings, but no web space to put them on

In 3rd gear, at 4000rpm, apx 70mph, the BLM reading was consistantly 124 with an IAT reading of 193. I assume this is an "ok" reading??

I also took screenshots of the O2 and BLM tables. When I get home tonight, I'll put them on the web somehow so you can see the charts.

Thanks for all your help in figuring this out, one step closer to perfection LOL

Thomas.

 

I would bet that if you put the stock chip back in and bump the base timing 2 more degrees that the BLM will go from that 124 to the 128.

 

Hmmm, so put the stock chip back in, and bump the timing to 8' advanced?

Will I loose performance from this? I guess the only real way to determine that would be to try it ...... I'll give it a shot and see what happens.

Thanks for the suggestion,

Thomas.

 

Well your loosing performance for running TOO rich now. Only thing you can do is test. At least you can monitor your progress. Save the performance chip for when you change to a LT1 cam or some other big mod and try it again.

 

I have a 55lb pod from a cop car, did the adjustable mod's and it will not lower beyond 12psi. WTF?

------------------
91 RS 5.0 TBI...Vortec heads...Edel Performer Intake...LT4 cam...1.6 Crane golds...TES headers...3"Dynomax exhaust...5spd... 3.08...Ultimate tbi...afpr...ZR 255-50's...Koni's

 

I just did a little more testing, and I think the IAT issue is a non-issue. When an ice cube is placed on the sensor, WinALDL's IAT reading went up, not down. When I held a lighter under the sensor, the reading came down. So I won't worry about that issue for now.

As for the running rich, here are the screenshots I took this morning. Any help with deciphering any relevent meaning from them, would be greatly appreciated!!

Here is the Raw Data recorded while I was in 3rd gear, at 4000rpm, doing ~70mph:


This is the BLM chart after driving to work. Mostly highway, except the last 5 miles is all stop & go:


Here is the O2 chart from the same ride in to work:


[This message has been edited by Stoopalini (edited December 12, 2001).]

 

I have got to get a laptop. That scanning software is great.

Makes auto x-ray look like using 1st grade pencils.

 

I also noticed that about the IAT being backwards. I'll talk to Joby about correcting that little bug.
It doesn't look too bad. It looks like you're about right since you aren't burning your own eproms. You'll either need to be slightly rich in open loop (cold start) and live with it or you can drop the fuel pressure but you'll run lean when you go to WOT. It really doesn't look too bad. Definatly running rich but you can't really control that unless you get into eprom burning.