Birmass

The FAQ notes that there are more possibilities for code 32 other than EGR if it's flashed. My idle SUCKS and this is the only code I'm gettin. It happens after I've been cruising for a while and will eventually go off after a while of driving. I have a custom chip that is supposed to have the EGR deleted. Assuming the chip has been burned right, why am I getting a 32 and why does my idle stink? This has been going on FOREVER and is pissing me off!!

Other pertinent info...

- not sure about O2 sensor
- custom chip by howell EFI
- holley 670 TBI - #65 injectors work fine
- IAC works fine
- TPS checks out
- the car idles BEAUTIFULLY if I start it up when it hasn't run for a while and don't move it at all. Once I drive for a few minutes it goes to hell.
- I've been getting backfiring(intake) while crusing at 1500 if I barely step on it in 5th gear.
- MAP sensor checks fine
- plugs and wires are good
- knock sensor is good

My first guess is the O2 sensor because it seems to be a mixture problem, but does that have anything to do with code 32? Besides O2 is there anything else to check that I haven't done?


------------------
88 firebird formula
350 Vortec TBI
214int/224exh, .471int/.491exh
Edelbrock headers
SIX-speed
Eats LS1's with a 2.73 open rear and 2 1/4 stock catback

My Formula

Vader

Birmass,

32 - EGR circuit fault, Baro circuit shorted, or MAP sensor circuit open. Baro sensors are generally only used on older carbureted engines and some TBIs.

Even though the PROM may have been coded to eliminate the EGR solenoid output and the resultant check for solenoid load, the programmer may have overlooked the factory portion of the program that will also set a 32 DTC when the EGR sticks open. If the EGR is not commanded on, and intake vaccum is weak (according to MAP sensor) the 32 can set due to a presumed stuck EGR valve.

Look at the MAP signal, and verify that intake vacuum is adequate. You might also have a problem with the MAP circuit itself, of a vacuum loss somewhere. Your intermittent backfiring under light loads indicates a very lean mixture.

- - - - - - - - - - - - - - - - - - - -

I'm experiencing a similar fight on an '84 Fiero with TBI. I get a notable lean miss at 1,300-1,800 RPM when cold which improves somewhat when it's warmed fully. New O2, new MAP, new TPS, new fuel filter, new air filter, stock PROM, better cam and ported head with larger valves, eliminated swirl ports, new injector, fuel pressure has been set from 15-25 PSI with no change (so I know the pump is good), new PCV, no vacuum leaks, no error codes except a periodic '44' after cruising fo a while. New distributor, plugs, wires test O.K., new cap and rotor, reluctor and pickup check O.K., coil tests O.K.

It runs better than most V-6s at WOT and under moderate-heavy accelleration, idles great at 850, starts when I even think of touching the key, but runs like crap just off idle position and at 1,300-1,800 RPM. ECM indicates it is always correcting toward the rich side. I thought it might have been the TPS having a dead spot, but it checked O.K. I installed a known good spare anyway. IAC works perfectly, TPS base is right on, and the EGR has been disconnected for diagnosis. Intake vacuum is about 17.5" at 850 idle.

Here's the real kick. It ran fine until it got hit while parked in front of my house. It sat for two months while I acquired all the necessary repair parts, then ran like this after the repairs were completed. I've looked for fuel delivery problems (pinched lines, etc., but it runs great at idle and above 15% throttle. The new cam and valves were installed in spring and it ran just splendidly most of the summer.

I'm ready to take a hammer to it to find the "loose" component. I'm thinking the PROM doesn't like my cam profile. Any thoughts?


------------------
Later,
Vader
------------------
"No matter how hard you try you can't stop us now"
Adobe Acrobat Reader 4.0

Birmass

Interesting. So your saying that my MAP sensor is not getting enough vacuum at idle and thus is calculating that loss as a vaccuum loss in the EGR? If 32 is always somehow associated with EGR then I guess they forgot to delete that part. This does imply some sort of vacuum confusion though. I put a new MAP sensor on and nothing changed, but I don't have a volt meter with me to check the signal until the end of the week when I'm home. Is there some other way I can test this? I don't know of any vacuum leaks though and if I start it up and not rev it or move the car it idles beautifully. This implies a sensor problem though and it won't set the 32 until I drive. AHHHH!!!!! It never ends!!!


Your problem is quite wierd too. I would assume a flat spot in the TPS like you said, but that doesn't seem to be it. Where was the car hit? Damn, I kept thinking of ideas like low vacuum, low fuel pressure, but you've gotten rid of those possibilities!

I think you're just running lean.



[This message has been edited by Birmass (edited December 04, 2000).]

Birmass

Also, what do you think my TPS voltage should be at?

Could increasing yours help?

------------------
88 firebird formula
350 Vortec TBI
214int/224exh, .471int/.491exh
Edelbrock headers
SIX-speed
Eats LS1's with a 2.73 open rear and 2 1/4 stock catback

My Formula

Vader

Birmass,

The code could also be a problem with the MAP, not just the EGR. Typically, the '32' that sets while cruising is because the EGR is not opening when it is commanded on by the ECM. If the programmer deleted the EGR provisions, this should not occur. A '32' from a stuck EGR would occur at idle of low RPMs under light loading.

If you want to see what the ECM is doing to the fuel mixture, use the Field Service Mode to monitor fuel adjustment after the engine is warmed.

My car was hit in the LF corner and there was little more than body damage (but plenty of that). The gauge holes on the space frame were off less than 1/4" from corner to corner, a variation that the frame shop said can occur through normal driving stresses on a 16-year old car.

Nothing around the fuel tank and lines appeared to have been damaged, and the pump will hold plenty of pressure. If this happened right after installing the cam this spring, I would have suspected PROM deficiency right away, but it didn't. I've never had this much frustration with a TBI.

------------------
Later,
Vader
------------------
"No matter how hard you try you can't stop us now"
Adobe Acrobat Reader 4.0

Birmass

Cool, I'll check the field service mode as soon as possible. Maybe it's my MAP and O2 combined.

I feel better now atleast. Although I'm not quite ready to take a hammer to it, I'm getting close

Red Devil

Birmass, are you sure the chip was burned for an '88? Some years have a temp sensor (I think yours does) and it could be possible that that may have been overlooked. Also make sure that the EGR vacuum line is still plugged. Also if you only have drivability problems after warm up I would definitely look into the O2 sensor.

Vader, here is a theory for you... the car got smacked, loosened up some carbon that was sitting somewhere in the EGR tract and then got sucked in somewhere causing a less than adequate flow through the EGR. This could possibly cause a lean condition as the ECU assumes some air is displaced by the exhaust gasses (not entirely sure of this function of the ECU). This combined with an aggressive cam could just touch off that dead spot. What do ya think?

------------------
"The people always have some champion whom they set over them and nurse into greatness... This and no other is the root from which a tyrant springs; when he first appears he is a protector.
-Plato

Birmass

Yeah, I actually sent my original chip to them so they could just copy it and modify the parameters. I won't be able to work on it till the weekend though.

Vader

RD,

Thanks for the idea. The cam is not that aggressive, just a bit better than the stock stick. The theory is a good on, but I've already had the EGR off to check it and teh manifold passages. The EGR was clean as a whistle when I reinstalled it after the engine work, adn was still clean. The manifold was thoroughly washed inside and out after its port work, but I'll try blowing through it again just for grins. When I pulled the EGRa couple of days ago to check it, the passages still looked very clean.

Birmass,

Even though the TPS on the TBI is not supposed to be adjustable, I have been able to alter the idle position voltage from 0.68VDC to 1.10VDC with no real changes. The ECM dutifully reads the base position and calculates throttle position regardless of the base voltage. The base is supposed to be under 1.0V.

If your oxygen sensor is more than 30-40,000 miles old, you might want to change it anyway. I replaced the sensor in the four-banger and my problem actually got a little worse. I went back to the old O2 to help. I'm betting that since the old sensor was reading a little higher that my mixture is on the rich side (typical of a weakening O2 sensor). In my case, the weaker O2 sensor is actually helping me by enriching the mix a bit. In your case, the EGR fault code might not be related to the O2, since they are not directly interdependant in the programming.

Whatever your problem is, it is definitely happening when you get to closed-loop mode. Either the ECM doesn't like one of the sensors or the PROM can't tolerate the current operating conditions (I'm beginning to suspect that is my problem). If you still have the original PROM, you might want to try that to compare operation. It certainly can't hurt anything.

Just for the sake of argument, I'm going to pull and reseat all the ECM connectors and PROM carrier in the roller skate to verify good connections and signals. The impact might have lodged something loose, and I'm running out of alternatives. I've yet to check the alternator for stray AC voltage (shorted diode), but I'm not experiencing problems at other RPM ranges and loads, so I'm not expecting to find anything unusual.

------------------
Later,
Vader
------------------
"No matter how hard you try you can't stop us now"
Adobe Acrobat Reader 4.0

Red Devil

Mmmm... Fiero. Anything other than stock is aggressive.
Do you know what ignition module is in there? Maybe something to look to. I'll think on it. Intriguing. What about your grounds?

Vader

RD,

I've pretty much ruled out the ignition system. I drove home from work today with the MAP sensor disconnected. The li'l scooter ran like it had a new pair of *********. The extra fuel from the backup mode tables was precisely what the physician specified.

I'm getting more evidence that my appropriate fuel curve is off the current fuel map for the stock arrangement. I've raised fuel pressure, but I'm going to do it again to try to remedy the problem. Field Service mode indicates that the ECM is always trying to adjust to the rich side, and by a significant amount. The MIL nearly stops flashing when I throttle up to the position where the worst performance occurs. Guess I might need a larger injector ir different PROM.

------------------
Later,
Vader
------------------
"No matter how hard you try you can't stop us now"
Adobe Acrobat Reader 4.0