NSW Corvettes
Technical Tips => Post 84 => Topic started by: glenco on April 16, 2015, 06:54:56 PM
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:lol: Hi all I think this is my first post on here? I have an 86 C4 that is driving me insane. It will run fine but then drop on to 6 cylinders for no reason & I have trouble getting to go over 100 kmh. Also seems to run rich? I have replaced just about everything under the bonnet but nothing seems to make any difference. Has anyone had this experience & what was the problem? Hope someone can help becuase it has got to the point were I dont want to drive the car anymore. Thanks all Glenn.
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Nah, this was your first post on here: :smile:
http://nswcorvettes.com.au/forum/index.php/topic,10419.msg1045950580.html#msg1045950580 (http://nswcorvettes.com.au/forum/index.php/topic,10419.msg1045950580.html#msg1045950580)
Hope a C4 expert here can offer you some tips. Nothing worse than an unreliable vehicle. No fun at all.
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Are you getting any codes? Service engine light on?
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Nah, this was your first post on here: :smile:
http://nswcorvettes.com.au/forum/index.php/topic,10419.msg1045950580.html#msg1045950580 (http://nswcorvettes.com.au/forum/index.php/topic,10419.msg1045950580.html#msg1045950580)
Hope a C4 expert here can offer you some tips. Nothing worse than an unreliable vehicle. No fun at all.
Cheers GTC, just shows how bad my memory is! And I didnt by that 69 either.
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Are you getting any codes? Service engine light on?
The service engine light is always on, has been ever since Ive had the car. And I do get codes, 3 in fact. They are 32,33 & 34. Any ideas? It points to being the maf sensor but I have tried 2 new ones & still the same.
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Bummer to hear your still having issue's Glenn :tears: might have to bight the bullet and take it to Steve at S.R.Performance. Get Steve to diagnose it on the dyno once and for all :huh:
Jethro
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Bummer to hear your still having issue's Glenn :tears: might have to bight the bullet and take it to Steve at S.R.Performance. Get Steve to diagnose it on the dyno once and for all :huh:
Jethro
How ya doin Jethro? Yeah Ive been thinking I might have to take it to someone matey, I keep chasing my tail it seems! Its the first car thats ever beaten me!! Where is S.R.Performance Jethro? You remember that I live at whoop whoop hey...
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http://www.srperformance.com.au/ (http://www.srperformance.com.au/)
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http://www.srperformance.com.au/ (http://www.srperformance.com.au/)
Thanks for the link GTC I'll give em a call :thumb:
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How ya doin Jethro? Yeah Ive been thinking I might have to take it to someone matey, I keep chasing my tail it seems! Its the first car thats ever beaten me!! Where is S.R.Performance Jethro? You remember that I live at whoop whoop hey...
Yeah Glen but if ya want to stop chasing your tail once and for all, you'll have to
a) to have to pay for it
b) it's not going to be in your next of the woods
c)you'll need to take it to someone who has all the gear
d)and you'll need to take it to someone that has all the experience
That's Steve at S.R. Performance brother :thumb:
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Yeah Glen but if ya want to stop chasing your tail once and for all, you'll have to
a) to have to pay for it
b) it's not going to be in your next of the woods
c)you'll need to take it to someone who has all the gear
d)and you'll need to take it to someone that has all the experience
That's Steve at S.R. Performance brother :thumb:
Yeah you're right Jethro, time to throw in the towel & get it sorted, I'll get on to Steve & sort something. Cheers bro :banghead:
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Glen, check your private message inbox.
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Had similar indication in my C4 a month ago. Was EGR diagnostic switch shorted.
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Had similar indication in my C4 a month ago. Was EGR diagnostic switch shorted.
Cheers sabre. That's something I haven't looked at yet. How did you find out the problem & did you put a new switch in?
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Just followed the fault flow chart for code 32. Measured the switch. Should be open cold and found it permanently closed. Stole a replacement from project car. New switch due soon from US. Suggest you also check the MAF burn off relays. They often cause problems.
Cheers sabre. That's something I haven't looked at yet. How did you find out the problem & did you put a new switch in?
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The service engine light is always on, has been ever since Ive had the car. And I do get codes, 3 in fact. They are 32,33 & 34. Any ideas? It points to being the maf sensor but I have tried 2 new ones & still the same.
Code #32: EGR System Failure.
Code #33: Mass Air Flow Sensor High.
Code #34: Mass Air Flow Sensor Low.
Did you disconnect the battery after swapping sensors? That will clear the codes. Check the wiring harness to the sensor is ok too.
This site might help - http://www.digitalcorvettes.com/forums/showthread.php?t=54543 (http://www.digitalcorvettes.com/forums/showthread.php?t=54543)
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Code #32: EGR System Failure.
Code #33: Mass Air Flow Sensor High.
Code #34: Mass Air Flow Sensor Low.
Did you disconnect the battery after swapping sensors? That will clear the codes. Check the wiring harness to the sensor is ok too.
This site might help - http://www.digitalcorvettes.com/forums/showthread.php?t=54543 (http://www.digitalcorvettes.com/forums/showthread.php?t=54543)
Thanks for that 77CVT. I have disconnected the battery each time I change something, but the problems always come back. To date I have tried 2 maf sensors & connector I have replaced maf relays I have replaced IAC & TPS. Have replaced evrything in the ignition system, & a new ECM, have replaced coolant temperature sensor & also O2 sensor as well as all new injectors and lastly a new fuel pump! You can see why it is driving me insane! Cheers
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Ahhhhh I remember those days when I had me C4 Glenn :banghead: :banghead: don't seem to have those I.T. gremlins with a 69 :drunk:
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Ahhhhh I remember those days when I had me C4 Glenn :banghead: :banghead: don't seem to have those I.T. gremlins with a 69 :drunk:
SO jethro your saying sell the c4 and buy a c3 preferably a 69/70 model ?
That is a way to sort the problems
Bfit
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SO jethro your saying sell the c4 and buy a c3 preferably a 69/70 model ?
That is a way to sort the problems
Bfit
No Bobby, just that C3 only needs Spark, Fuel & Air no computers no injection simple as an ole skool fooken tractor :drivedevil:
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No Bobby, just that C3 only needs Spark, Fuel & Air no computers no injection simple as an ole skool fooken tractor :drivedevil:
:grin: Dont worry Jethro, Ive been thinkin that for a while! Pull the motor out of my T bucket & stuff it in the corvette! It would be way faster as well matey :thumb:
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I read a write up on a C4 with a fuel injected 540 BB a few weeks back
Make for a quick C4
Bfit
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I'm no authority on C4s, but I do recall a tale of a C4 that was throwing weird engine codes and proving crazy difficult to diagnose. The problem ended up being a byproduct of a poor wiring job done long ago by the converter and eventually causing issues years later.
Just a thought.
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I had a similar issue with my old C4 thats why I had the spare new MAF i gave to Glenn. Chased it and chase it, then took it to two locally supposedly top flight tune shops in the gong.... replaced this ..... replace that..... :tears: :tears: better but not fixed
Eventually bit the bullet and took it to S.R. he and he's I.T bro spent some time on it but and :thumb:
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I'm no authority on C4s, but I do recall a tale of a C4 that was throwing weird engine codes and proving crazy difficult to diagnose. The problem ended up being a byproduct of a poor wiring job done long ago by the converter and eventually causing issues years later.
Just a thought.
It seems the possibilities for problems are endless in a c4 :banghead: Anyone got a nice c3 they want to trade?? :huh:
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Come on Glenn you have a Beaut C4 and it's hopefully not that big a fix just need to get it to someone that knows what they are talking bout.... :thumb:
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It seems the possibilities for problems are endless in a c4 :banghead:
You can get such problems with any car that has computerised engine management. An experienced C4 mechanic should be able to sort it out.
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Has the issue with this car been sorted yet ?
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Disc battery for a minute resets codes, the codes you have are as stated before. All centre around the MAF and the relays. The relays must be the correct part # for MAF and MAF burn off ie coil res and contact resistance. Strange your not getting a 36. It's very seldom the MAF. 33 & 34 are set in the first ~30sec (may not show on the screen for a minute or two) 33 means that on START UP when in the choke period there is too much air being draw thru the MAF whilst 34 is not enough air - check idle set up and the choke injector is ok - yes that's injector #9 (inj cleaner only runs thru it for ~8 or so secs, maybe not long enough to clean years of crap. Next issue is wiring and connectors which harden, become loose etc to the relays. The relays, connectors etc are usually pretty close to #7 manifold. Check your Batt, leads, and earths. I have had your problem for some time, I fiddle under the hood and it goes for months, then I do something else and it's back, however, I also get heat soak into my starter and restating mimics a low to flat battery, this puts low volts into the computer which brings in 33,34,36 and for good measure sometimes a 42 (EST module) so the start may have a bad "ping" but as soon as the volts comes up the module runs ok. These codes are for Start Up conditions only and should not effect warm running operation. That bloody LIGHT is just so annoying.
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Problem not sorted yet. Thanks vettech, I have checked all the wiring to the maf relays when I changed them,I bought them from Ecklers in the u.s. so I assume they are correct relays. Also my car has had the cold start injector removed, could that still be a problem?
It would be great to be able to drive vette again, I do enjoy it when its running properly :drivedevil: Cherrs all :thumb:
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It may explain the code 33 or 34. If all else is STD can I ask why is it removed. If when cold you apply foot to peddle to get it started then this will draw more air and set a code 33. If you don't, it may detect low air and set 34. Once set they stay till a hard reset. Battery on pad is low - by for now
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Oh - be fore this shuts me off - even though these codes are set, they should not effect the drive ability of the car. 33/34 are only detected in first ~30 sec upon start up. 36 is the MAF burn off - the actual burn off is activated if the car is run for "X" time and then stopped. Relay supplies 12v to the hot wire and heats for "x" seconds to burn off any grim / residue stuck to the wire. This wire is hot whilst running and its temperature is related to its resistance thus more air cools it - more air needs more fuel, computer reads resistance and varies the fuel accordingly.
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re reading the thread it appears that most electrical bits have been replaced,Is this a lhd or a converted rhd car ? if its a converted car maybe its time to look at some of the wiring
It may be fuel injected but it still only needs air fuel and spark to work ....just more wires than a carby car and a few more sensors.
I had a no start issue with my car that had me stumped for a while (original lhd still),pulled my hair out until I found the broken wire that didn't let current run through to injectors
I also had a new memcal made that installed a tune from an 89 model that deletes the cold start and I had the egr system programed out ...makes the electronics a little simpler
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Very interesting! I'm testing my memory here, but didn't GM change to sequential injection in 88, I suppose it would not make much difference, instead of injecting all odds then all evens, it would do each individually. Give better power + econ, but by 88 they all had all Alloy Heads and roller rockers. My black book only goes to 90 and I'm now having self doubt. Umm maybe SHE is right - dementia setting in.........
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Come on Glenn you have a Beaut C4 and it's hopefully not that big a fix just need to get it to someone that knows what they are talking bout.... :thumb:
Come on Glenn bite the bullet son ! Ring Steve at S.R.Perforance.... :thumb:
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Buying C3 would be a good alternative.
Bfit
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any updates ?