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C.A.T.S. data analysis Corvette LT1 1992

Old 06-12-2018, 05:33 PM
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Filip Rzarov
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Default C.A.T.S. data analysis Corvette LT1 1992

Hi Guys


Im new to this forum. Im trying to solve a problem of my misfiring Corvette C4 LT1 1992 . The cars drives OK when cold . When it hits 230 deg F it starts stalling like sudden power loss between 1000 and 2500rpm and then drives OK . Iddles ok . Stalling occures when puting your foot down. It either stalls as someone ripped of battery cable and put it back on before the engine stopped .. (sometimes the engine stops ) (10% of the time when hot ) . OR just it goes in acceleration with couple misfires (like hesitations ) until it hits 2500 RPM and drives OK from there .


Only when engine gets hot - above 230 F

I have recorded a CATS while driving in town with all the possible engine parameters . Stalling in this file happens at 3948 sec and 4038 time frame


I suspect the optispark - (although EGR seems inactive - from what I can tell )

Anybody with experience in CATS data analysis is most welcome . Please reply and I can send the .dcf file.

Than you very much in advance ,
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Old 06-12-2018, 10:06 PM
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Codes? Never heard of CATS. When car acts up what happens with tach signal? The was a thread a while back related to using o scope to monitor opti signals to ecm. You might search for it.
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Old 06-12-2018, 10:30 PM
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Zip and attach your DataCat *.dcf file here if you can. I will take a look at it.
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Old 06-13-2018, 01:26 AM
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Originally Posted by tequilaboy View Post
Zip and attach your DataCat *.dcf file here if you can. I will take a look at it.

I would really appreciate it. Attached is the zipped .dcf file.

Thank you very much
Attached Files
File Type: zip
test 1.zip (192.8 KB, 2 views)
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Old 06-13-2018, 03:09 AM
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Vis Croceus
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Originally Posted by Filip Rzarov View Post
Hi Guys


Im new to this forum. Im trying to solve a problem of my misfiring Corvette C4 LT1 1992 . The cars drives OK when cold . When it hits 230 deg F it starts stalling like sudden power loss between 1000 and 2500rpm and then drives OK . Iddles ok . Stalling occures when puting your foot down. It either stalls as someone ripped of battery cable and put it back on before the engine stopped .. (sometimes the engine stops ) (10% of the time when hot ) . OR just it goes in acceleration with couple misfires (like hesitations ) until it hits 2500 RPM and drives OK from there .


Only when engine gets hot - above 230 F

I have recorded a CATS while driving in town with all the possible engine parameters . Stalling in this file happens at 3948 sec and 4038 time frame


I suspect the optispark - (although EGR seems inactive - from what I can tell )

Anybody with experience in CATS data analysis is most welcome . Please reply and I can send the .dcf file.

Than you very much in advance ,
The general symptoms you describe almost always point to O2 sensors, but I would normally expect it to start at a lower temperature.
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Old 06-13-2018, 03:15 AM
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I Did kind of tried the O2 sensors..from what I know if you pull the conectors off them there is just a reference value to ECM and car should not top its performance and emissions - but should not stall. I did give it a ride with the sensors off-and the symptoms were there again.

I will order new anyway o2 anyway...but I dont think they are my major issue.
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Old 06-13-2018, 03:24 AM
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Originally Posted by Filip Rzarov View Post
I Did kind of tried the O2 sensors..from what I know if you pull the conectors off them there is just a reference value to ECM and car should not top its performance and emissions - but should not stall. I did give it a ride with the sensors off-and the symptoms were there again.

I will order new anyway o2 anyway...but I dont think they are my major issue.
If you unplugged them and it didn't change, then it's not the O2s.

The other common temperature-related problem on these cars is overheating ICM, but your symptoms don't really sound like that.

You're right to start looking at logs at this point.

No codes?

If you can export to xls from datacat, that will get you a larger number of people looking at your log.

Also post it on camaroz28.com. There's a guy over there who likes to help people with LT1 logs and has been doing it for decades now.

Last edited by Vis Croceus; 06-13-2018 at 03:25 AM.
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Old 06-13-2018, 03:28 AM
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Thanks

No codes unfortunately. I will try to export to other format.

thanks
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Old 06-13-2018, 11:36 AM
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Originally Posted by Kevova View Post
Codes? Never heard of CATS. When car acts up what happens with tach signal? The was a thread a while back related to using o scope to monitor opti signals to ecm. You might search for it.
CATS is tuning software. It's been long enough since I used it that I don't remember if it does data logging.
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Old 06-13-2018, 12:46 PM
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Basic observations: Both O2 sensors are functional and are in phase with each other and show good symmetry, so both banks are showing the same general behavior.

Very rich off throttle with both long term BLMs bottomed out at 108. A bit lean otherwise but not a big concern.

I would investigate the light load over fueling first. Maybe a regulator leaking fuel into the intake, or multiple injectors leaking (both banks).

I don't see any stalling at the indicated frames, so maybe wrong file was uploaded??? I do see rpm drop in a couple frames (1022 and 2478, but looks like a data anomaly more than a stall).

Also curious why oil and coolant temps so hot? What is your climate like (are you in Death Valley)?
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