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TBI injection Running rich on idle

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bo9ager

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Kuwait
Hi,

I have bought a 1988 Blazer that had a 454 engine swapped instead of the original 350 and it has a TBI, My problem is that the car runs way too rich and by reading some related post and some YouTube videos i have tested the common causes for a rich idle which are:

MAP Sensor 5 to 0.5
TPS Sensor .5 to 5

and they all had good signals and were in range from what i have been reading, I found out that i don't have an O2 sensor and I just purchased OBD1 scanner which will arrive in mid March since i don't live in the US, would be great if i can get some pointers on how to fix this problem, Plus I know it has this cam on it cca-k11-601-8 from comp cams.

Thanks:laugh:
 
Last edited:
Well the O2 sensor was probably removed so it could run Open Loop. Actaully most GM EFI vehicles sent to Kuwait were Open Loop leaded fuel so it probably never had one.

With that cam it's going to be rich and hard to tune for a decent idle, it's not menat to run under 2000 RPM... not a good EFI cam. Can be tuned to run well but Open Loop, at least at idle.

Hydraulic roller tappet

Basic Operating RPM Range:2,000-5,800

Intake Duration at 050 inch Lift:235

Exhaust Duration at 050 inch Lift:249

Duration at 050 inch Lift:235 int./249 exh.

Advertised Intake Duration:291

Advertised Exhaust Duration:311

Advertised Duration:291 int./311 exh.

Intake Valve Lift with Factory Rocker Arm Ratio:0.558 in.

Exhaust Valve Lift with Factory Rocker Arm Ratio:0.542 in.

Valve Lift with Factory Rocker Arm Ratio:0.588 int./0.542 exh.

Lobe Separation (degrees):107

Grind Number:291THR7

Computer-Controlled Compatible:No

Lifters Included:Yes

Lifter Style:Hydraulic roller
 
Thanks for the reply,

So what do you suppose I should do to fix this problem, Change the cam to a stock one?
If there is another way can you please tell me.
 
That cam needs a custom tuned chip to run properly. It needs way more spark advance at idle, higher idle, less fuel at idle. Probably more fuel pressure then a stock system for WOT high RPM.

Also does the new motor have correct injectors? They are differant from 5.7L to 7.4L so is the chip in ECM, but even the correct chip for 7.4L would not run properly with that cam.

Anyone tune chips there in Kuwait? Dyno shop? Performance store may know someone?

How much is gas there now? Still leaded fuel?
 
Oooh then i guess the better option is to just change the cam, The engine was swapped with a 454 tbi engine so i guess whatever was on it was the right one for it, I've looked everywhere and it seems that OBD1 vehicles don't get tuned in dyno garages in Kuwait,

Our gas is unleaded and is 2.3 dollars a liter ;D
 
Much better cam!

Lot of work though. You sure no one there can burn a chip? How about a datalog to see what it's doing? Have you checked for error codes? Fuel pressure?

The cam that is in there is not a very good cam for city driving and even worse for an Auto trans without a higher stall speed tourque converter. Horible for fuel milage. Great for WOT horse power!
 
Im Pretty sure no one can burn a chip but they might datalog, anyways i wasnt planning on having something that is not a daily driver so i must change the cam, will the new one be a daily driver ??

Thanks for the help, the scanner Im waiting for is INNOVA 3140 Diagnostic Code Scanner for OBDI and OBDII Vehicles, hope its good enough
 
The new cam you picked is a daily driver and good performance! Good choice.

Not sure on scanner? I have a AtuoXray 7000 that does good for OBDI and OBDII. Do you have a laptop? You can buy a cable and get software to work on laptop that will read codes and watch or record data.
 
Thanks alot that's good to hear about the new cam cuz i just bought it, and about the scanner i think its pretty much like the one you have so i think its OK, I will update you as soon as I scan it or change the cam to see if i solved the problem :)
 
I'm now working on the cam, thanks for the advice : ), I have another question concerning the headers, is there any brand that provides headers for a blazer with a 454 engine, or is there a car that shares the same platform of the blazer and uses a 454 engine, if not then please refer me to some place in the US that can provide me with a bolt on headers even if it is custom since I don't want Kuwait's exhaust fabricators to do me one they do an awful job on the cars I've seen
 
I'm now working on the cam, thanks for the advice : ), I have another question concerning the headers, is there any brand that provides headers for a blazer with a 454 engine, or is there a car that shares the same platform of the blazer and uses a 454 engine, if not then please refer me to some place in the US that can provide me with a bolt on headers even if it is custom since I don't want Kuwait's exhaust fabricators to do me one they do an awful job on the cars I've seen
 
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