C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

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Old Mar 23, 2010 | 10:56 PM
  #21  
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Allright, I'll replace the relays, and if necessary, order a new maf. It was nice to drive it a bit today though. Buying a c4 should include a year long College course in service and maintanence. Thanks again, all
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Old Mar 23, 2010 | 11:04 PM
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Is your code 22, gone now ??
If so, plug in the MAF and see if the 33 re-appears.
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Old Mar 23, 2010 | 11:54 PM
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Yes, I installed a new tps today and adjusted it to .54v. 22 is gone, only showing 33 now. Shure is odd that tps and maf crapped out at the same time...I'll go see ol' Curt Warner tomorrow and get some relays form the dealer. I know I'll catch hell for this but, I'm assuming the ecm is good since it runs well without the maf? 15 years ago my '88 IROC had similar symptoms and I ignorantly replaced sensors to no avail. Looking for different outcome this time, I appriciate the help.
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Old Mar 24, 2010 | 12:10 AM
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Originally Posted by engle1147

ECM/PCM are programed (chipped on early models without MAP backup) with an extra "limp home" mode that gives the computer backup default data in case of failure. The car will run like crap with the MAF disconnected on earlier models unless it is a newer model that has both a MAP & MAF combined setup.
OK the 85-87 were MAF only. So where/what are the rest of L98's configuration?

Anyone? Anyone? Bueller?
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Old Mar 24, 2010 | 02:14 AM
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Originally Posted by boardroomjimmy
Yes, I installed a new tps today and adjusted it to .54v. 22 is gone, only showing 33 now. Shure is odd that tps and maf crapped out at the same time...I'll go see ol' Curt Warner tomorrow and get some relays form the dealer. I know I'll catch hell for this but, I'm assuming the ecm is good since it runs well without the maf? 15 years ago my '88 IROC had similar symptoms and I ignorantly replaced sensors to no avail. Looking for different outcome this time, I appriciate the help.
Do you have a stock TB or an aftermarket one?

The reason I ask,if you have a TB that is not adjusted properly for the minimum air speed,you will get a code 33.

The ecm will see an unrealistic airflow and set that code.

I had this problem with an 52 MM TB.It was not adjusted right and it took a while to figure it out. This can still happen on the stock TB if someone adjusted the screw and did not do the proper adjustments.

That is something important to check.
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Old Mar 24, 2010 | 08:12 AM
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Originally Posted by boardroomjimmy
Yes, I installed a new tps today and adjusted it to .54v. 22 is gone, only showing 33 now. Shure is odd that tps and maf crapped out at the same time.
Did you set the minimun idle along with TPS idle voltage ?
Have you tried to clear the code 33, run it again, and check for 33 again.

If the 33 is still there after setting minimum idle and TPS idle voltage, follow the flow chart to diagnose the problem.

http://members.shaw.ca/corvette86/Code%2033.pdf
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Old Mar 24, 2010 | 11:25 AM
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Originally Posted by AGENT 86
Did you set the minimun idle along with TPS idle voltage ?
Have you tried to clear the code 33, run it again, and check for 33 again.

If the 33 is still there after setting minimum idle and TPS idle voltage, follow the flow chart to diagnose the problem.

http://members.shaw.ca/corvette86/Code%2033.pdf
No, I didn't set min. idle, Yes, I did clear codes and 33 popped right back up(no 22). It runs poorly with maf plugged in, great w/o it. I'll follow the flow chart to diagnose. Thanks for posting the process. I'm gonna replace the relays for insurance, then I'll follow troubleshooting sequence. Motor is 100% stock.
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Old Mar 24, 2010 | 11:43 AM
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OK the 85-87 were MAF only. So where/what are the rest of L98's configuration?

So were the '88 & '89. '90 & '91 were Speed Density or MAP. LT motors eventually used a dual strategy - I thought I allready posted this.
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Old Mar 24, 2010 | 03:26 PM
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85-89 MAF
91-92 Speed density using a MAP sensor
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Old Mar 24, 2010 | 05:14 PM
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Went to dealer this morning and picked up nu relays. The ones in there have been replaced b-4, but were the correct pn#. Cleaned the connectors, cleared the codes, plugged maf back in and......It is running perfect. no sas, 25mpg on hi-way. All seems good for today, except for the seat controls. I'll start nu post on that later. At least it's running. Thanks, C.F.
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Old Mar 24, 2010 | 06:18 PM
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Brent, Im telling you, with this bunch of guys on here, and the accumulated knowledge they possess, there isn't much on a C4 that they can't help you figure out.....WW
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Old Mar 25, 2010 | 12:46 AM
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Originally Posted by boardroomjimmy
Went to dealer this morning and picked up nu relays. The ones in there have been replaced b-4, but were the correct pn#. Cleaned the connectors, cleared the codes, plugged maf back in and......It is running perfect. no sas, 25mpg on hi-way. All seems good for today, except for the seat controls. I'll start nu post on that later. At least it's running. Thanks, C.F.
Please, please, check your under the hood wiring harnesses at the connector ends for exposed copper. Big problem with the early C4's. The fix is the re-insulate with shrink tube or tape.

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