Let me say 1st that I fixed the problem that I was having before. The MAF meter wasn't happy before the supercharger.
Anyone know which sensors will make the car run in "limp home" mode?

From what I understand... when its in "limp home" mode.... your car is running off of very basic mapping that is like a default and is stored in the CalPak. The absence of certain sensors or erroneous readings will make the car go into that "limp home" mode.

My car will not run in anything other than "limp home" mode... and I get no computer codes. Get 12's everytime.

The car was doing great until yesterday... all of a sudden it starts running rich. I know when it runs extremely rich... that it is running from the default data in the CalPak.... rather than the Ed Wright chip. The CalPak is factory, and thinks that I have 19lb injectors... not 36lb. Thats why when its running extremely rich... I know its in that limp mode.

What I can't figure out.... is why is my car going to this "limp" mode... If there was a sensor problem... to make it go into that mode... how come I get no codes? Clueless...once again. I think my car is posessed.

Any Ideas?

 

What does the scanner say about your ECM? i.e. What is the ECM seeing from the sensors?

What makes you say it is in Limp mode?

 

I ran in limp mode once because one of the ecm fuses was blown. Worth checking all the fuses.

 

I thought I explained it...but it is confusing.

My injectors are 36lb now... but whenever my car goes in limp mode... it uses the CalPak to run the car... which is setup for stock 19lb injectors.

The weirdest thing is... I get no codes.... why would it go into limp mode for no reason... and how could the car run wide open rich without any codes being stored???
I mean did GM give out Free toasters with the '85 ECM??? The car won't even stay running it is so rich... and black soot (fuel) is puffing out of the tailpipes. Yet... NO CODES??? NOT ONE?

It makes no sense for the car to be running that bad... and not trip a code. I'm like... what sensor is telling the car to pump that much gas.... and come to the conclusion... no code = no bad sensor.... it must be forced into "limp mode" and that would explain the richness.... because of the calpak running 36 lbs injectors with a 19lb map.

Anyone want a free Corvette? I seriously debated leavin it on the side of the road. Been nothing but problems lately. I have a Nissan 300ZX with 450 RWHP... that should of been enuf. But I wanted this vette... and had to have it. Anyway... I have had the nissan going on 10 years.. and know it inside and out - no guessing whats wrong when something goes goofy with it. But since the Corvette is new to me... I have having to learn the car... just like I did my Z. I am just a lil impatient. Bare with me folks... I love the Vette Equally.

 

You should be getting a code 45 if it is running rich. If the oxygen sensor remain above 0.7 volts for 1 minute the code will be set if in closed loop. If your running that rich, you may have fouled the oxygen sensor. If you can scan your car you can tell if the sensor is working. Before I got my laptop, I brought my desk-top computer into the garage and hooked it up. Use Winaldl and a home made cable.

 

>> If your running that rich, you may have fouled the oxygen sensor.

To expand on this a little - the fouled O2 sensor may now fail to respond to O2 content, so you get no code. Or maybe it's falsely indicating a lean mix, so more fuel is added. Wouldn't take many extra milliseconds on the PW for 36's to overwhelm. A vacuum leak would have the same consequence, by why is your problem only now and then? Is the CCP purge line hooked up? EGR vacuum line? Both of these would leak vacuum only when commanded on. Is the problem temp sensitive?

>> If you can scan your car you can tell if the sensor is working.

Exactly my thought. Would be my first step FWIW.

 

First off, you aren't running in limp home mode. If you are, you haven't provided enough info to suggest you are. Since it looks like you are taking stabs at it, I'm going to take one.

[stab]

You IAC is going full open. Once it goes full open, you will hear a slight whistle/sucking sound near the airfilter. It will be somewhat pronounced. You will be running with 10 inches of vacuum instead of 16 at idle when this happens. The low vacuum will not correspond to the MAF and TPS, Air is being diverted around the throttle plates instead of reacting with the TPS sensor.

Your O2s will be high. Your pulsewidths won't know what the hell to do. You'll turn down fuel pressure in an attemp to make it all correct. It won't.

Also, since you are not in limp home mode (in my mind at least), a scanner WILL connect and you will see your IAC counts go up to 160. If you are really in limp, a scanner will not connect.

[/stab]

Doc-You talking about the owners manual :jester

 

The AIC thing is what I am going to look at... That makes sense. I am going to swap the 02 sensor (have a spare). Reset the Computer, Idle and check really really good for vaccuum leaks.

I am going to remove the CALPAK... (I know I will get a "missing" code... but then I will know if it doesn't run at all... then it was in Limp Mode.

If it still runs... then I know its one of the sensors... and will have to manually check it.

AND MOST IMPORTANTLY....

Where can I get this WINALDL SOFTWARE??? I have an extra pc that I could put out in the garage... easily... and it sounds like I need this.

I am GM Tuning DUMB.... please tell me what I need... to scan IAC's and codes using a computer. I am a Elec. tech and VERY computer literate.

Tell me what software, where to get it... can someone email me it? What cable I need... (or do i just cut up a Din 9, 15, or 25? Does it have to be Null modem?

Sounds like I need to do this.... Could I get you guys to point me in the right direction?

 

Here's the link:
http://www.winaldl.webhop.net/

I had one computer that it wouldn't work on but two others that it did. You can buy premade cables but you should be able to make your own with radio shack parts. Once you look at the sensor readings, you'll know where the problem is. Keep us posted.

 

I am like you guys on the Nissan Z board. And I see people posting these petty problems...and I read over them lots of times... thinking... man... thats simple.

I am glad that you didn't skip over me on this. I really appreciate you taking the time to write stuff that you learned years and years ago. I am a big Do-it-yourselfer ... but it just takes knowledge on some things. I'm sure I can get it going now... with the info and insight you have provided....

Thanks!
Danny

 

Several times now I have seen a maf sensor fail-it starts out intermittant, then slowly gets worse. It'll stall out at idle, part throttle (especially with a sc) run like crap, but still do ok at wot. It won't set a code!!! It'll finally set a code when it's about totally dead.
If you catch it when it's acting up and it won't idle-try unplugging the maf-if it then will idle (and it should set a code then) it's the maf...
Also with a sc and a maf-leave the heatsinks in.....
Oh yea-with one sensor unplugged or finally noted by the ecm to be failed-it will go into "failsoft" mode; it uses a backup table for that sensor only.


[Modified by drive it, 8:01 PM 9/19/2002]

 

I checked everything... even "most" of the fuses... like the important ones... ecm, inj, etc.

I was looking at it late last night... and was bout to give up for the night. A buddy was over there... and I told him... "see, I checked all the fuses". But decided to check them again.

"GAUGES" - That fuse was blown... but all my gauges worked???? I put a new fuse in it... and the car was FIXED ! ! !!

U tell me.... I'm clueless on that one... but my buddy was witness to it.

 

It seems like the little things cause the most problems and are the toughest to find. Glad it's fixed :cheers: