Need Urgent Help!
Thread Starter
4th Gear
Joined: Jul 2012
Posts: 4
Likes: 0
Need Urgent Help!
Hi Everyone..I have a problem with my 1988 C4, the more I try to hit on the gas the less throttle i get and some smoke starts going out from the exhaust...they told me change the TPS, I did but the same problem is still there..today they told me i should buy the manifold pressure sensor and the fuel temperature sensor...do you think this will help? or I will still have to change the EGR valve? Thanks!
Burning Brakes
Joined: May 2011
Posts: 838
Likes: 2
From: Louisville Ky
Hi Everyone..I have a problem with my 1988 C4, the more I try to hit on the gas the less throttle i get and some smoke starts going out from the exhaust...they told me change the TPS, I did but the same problem is still there..today they told me i should buy the manifold pressure sensor and the fuel temperature sensor...do you think this will help? or I will still have to change the EGR valve? Thanks!
you have a MAF, not the MAP, but same animal. you can try unplugging it and the ecm will use a default setting. if it runs ok, that is a clue.
Race Director
Joined: Apr 2000
Posts: 15,344
Likes: 4,009
From: Texas
No, but the "throw parts at it" approach will certainly empty your wallet quickly. 
Who is "they" that's telling you all of this?
Do some trouble-shooting.
Is the fuel pressure regulator ok?
What's the fuel pressure?
Does the fuel pressure hold?
Ohm check the injectors
Is the cold-start injector ok?
Are there any codes? If so, what are they?
Did you check the EGR valve? If not, why do you want to replace it?
What's the timing set at? Did you check it properly?
or....just keep throwing parts at it. You might get lucky or you might have to spend a few thousand dollars.
Who is "they" that's telling you all of this?
Do some trouble-shooting.
Is the fuel pressure regulator ok?
What's the fuel pressure?
Does the fuel pressure hold?
Ohm check the injectors
Is the cold-start injector ok?
Are there any codes? If so, what are they?
Did you check the EGR valve? If not, why do you want to replace it?
What's the timing set at? Did you check it properly?
or....just keep throwing parts at it. You might get lucky or you might have to spend a few thousand dollars.
Thread Starter
4th Gear
Joined: Jul 2012
Posts: 4
Likes: 0
The problem is that I looked everywhere in Dubai for someone who can check the system, they all can check cars that are not older than 1991 :S...the software they have doesnt support 88 C4s.
Howcome its MAF and not MAP? I bought it from rockauto online and they mentioned it is MAP, please dont tell me i bought the wrong item
this means ill have to wait for another week..
Ill try unplugging the MAF
Howcome its MAF and not MAP? I bought it from rockauto online and they mentioned it is MAP, please dont tell me i bought the wrong item
this means ill have to wait for another week..Ill try unplugging the MAF
Burning Brakes
Joined: May 2011
Posts: 838
Likes: 2
From: Louisville Ky
The problem is that I looked everywhere in Dubai for someone who can check the system, they all can check cars that are not older than 1991 :S...the software they have doesnt support 88 C4s.
Howcome its MAF and not MAP? I bought it from rockauto online and they mentioned it is MAP, please dont tell me i bought the wrong item this means ill have to wait for another week..
Ill try unplugging the MAF
Howcome its MAF and not MAP? I bought it from rockauto online and they mentioned it is MAP, please dont tell me i bought the wrong item
this means ill have to wait for another week..Ill try unplugging the MAF
I assume black, rich smoke, but you didn't say. that can point to coolant temp sensor, if you have a code 15 or 14. also injectors, fuel press regulator.
I am guessing that you are not familiar with pulling codes yourself, thru aldl?
Last edited by joe paco; Jul 10, 2012 at 05:04 PM. Reason: correct to 15
Burning Brakes
Joined: May 2011
Posts: 838
Likes: 2
From: Louisville Ky
codes
Last edited by joe paco; Jul 10, 2012 at 04:59 PM. Reason: add
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Race Director
Joined: Apr 2000
Posts: 15,344
Likes: 4,009
From: Texas
The problem is that I looked everywhere in Dubai for someone who can check the system, they all can check cars that are not older than 1991 :S...the software they have doesnt support 88 C4s.
Howcome its MAF and not MAP? I bought it from rockauto online and they mentioned it is MAP, please dont tell me i bought the wrong item this means ill have to wait for another week..
Ill try unplugging the MAF
Howcome its MAF and not MAP? I bought it from rockauto online and they mentioned it is MAP, please dont tell me i bought the wrong item
this means ill have to wait for another week..Ill try unplugging the MAF
Got it.Trouble-shoot the items I mentioned above.
- The fuel pressure regulator is under the plenum towards the rear. Pull the vacuum line off. If there is fuel in it, the regulator is bad.
- Fuel pressure should be 39-43psi and hold with the key off, slowly bleeding down ~10psi over the course of 20-30 minutes
- Injectors should ohm test 15-16 ohms hot & cold. If an injector is over or under, it's bad.
- Remove the cold start injector and check for signs of leakage
The EGR isn't the issue. You'll get rough running, but not the other symptoms you describe. Nonetheless, you can remove it and verify it fully closes.
- How to check L98 base timing is well documented. A quick search will yield multiple threads. The cliff notes: Disconnect the ESC wire. Start the engine. Check timing...should be 6* BTDC, although it'll run fine anywhere between 4* BTDC and 10* BTDC.
For the record...your '88 is a MAF car. It also has a MAP sensor. The MAP sensor is used to keep the car running if the MAF fails. '90 L98 cars switched to Speed Density, using only the MAP (no MAF on the car). '91-'93 are also MAP cars (no MAF). '94-'96 cars switched back to MAF with MAP as a back-up.
Thread Starter
4th Gear
Joined: Jul 2012
Posts: 4
Likes: 0
Sorry for replying late. thank you so much, this is very informative..i will try all those tomorrow or day after...when u mentioned the coolant temperature sensor u reminded me of something, i have the "low coolant" alert always on! could the reason be that the sensor is not working?