Problems with my 85
Thread Starter
Heel & Toe
Joined: Jun 2009
Posts: 20
Likes: 0
From: Opelika Alabama
Problems with my 85
Ok fellas here it is when i first start the car up and drive it it drives great but after about 15-20 mins it starts missing almost i dont understand it it has (It is standard bore standard stroke 350 tuned port injection motor. It has fully reworked 64cc vortec heads with 2.02in and 1.60ex Manley swirl tip valves, ported and polished with Harland Sharp aluminum roller rockers, chromoly pushrods with guide plates, Comp cams camshaft .520in .515ex lift 268 duration and 113 LSA. Comp cams valve springs, Comp cams lifters, flat top pistons, Clevite 77 bearings, Total Seal moly piston rings, Tune Port Induction Systems billet smog pump delete kit, T.P.I.S. billet adjustable fuel pressure regulator, MSD 6AL ignition system, MSD wires, new distributor, module, capacitor, cap, rotor, coil, alternator, water pump, front shocks and all new sensors. Spec stage 2 clutch, new slave cylinder, new clutch master cylinder, new pilot bushing, new throwout bearing. It has a manual 4+3 transmission)
HELP PLEASE!!!!!
HELP PLEASE!!!!!
Drifting
Joined: May 2006
Posts: 1,428
Likes: 7
From: Chewelah Wa
Under what conditions does the miss show up? Under acceleration? RPM? How is the idle? Fuel pressure? Stock injectors?Vv Check for vacuum leaks? Thats a whole lot of motor for a stock TPI intake and maybe the stock tune. Very curious as to how well this combo would run as I also have a 85.
Drifting
Joined: May 2002
Posts: 1,509
Likes: 3
From: Hazel Park MI
Wow man, that's a ton of stuff done to it. RR loose? Stock injectors going out? Your rundown of parts doesn't list any other type of injector than stock, if I read correctly. Demonic gives a good start for diagnoses......
Le Mans Master
Joined: Mar 2004
Posts: 5,107
Likes: 171
From: Dublin CA
You gave us a LONG list of things that have been upgraded. BUT there is no mention of the chip. 
You can alter many things, but once you change out the cam you will need a new chip. My guess is that the car is running off the computer tables from the original chip for the first 10-15 minutes until it is warm. Then it starts to read the sensor information and goes and compares this to your computer tables and that is the point where things go wrong.
You can alter many things, but once you change out the cam you will need a new chip. My guess is that the car is running off the computer tables from the original chip for the first 10-15 minutes until it is warm. Then it starts to read the sensor information and goes and compares this to your computer tables and that is the point where things go wrong.
Melting Slicks
Joined: May 2001
Posts: 3,270
Likes: 26
From: Winchester VA
Cruise-In V Veteran
You gave us a LONG list of things that have been upgraded. BUT there is no mention of the chip. You can alter many things, but once you change out the cam you will need a new chip. My guess is that the car is running off the computer tables from the original chip for the first 10-15 minutes until it is warm. Then it starts to read the sensor information and goes and compares this to your computer tables and that is the point where things go wrong.
You can alter many things, but once you change out the cam you will need a new chip. My guess is that the car is running off the computer tables from the original chip for the first 10-15 minutes until it is warm. Then it starts to read the sensor information and goes and compares this to your computer tables and that is the point where things go wrong.Did this start happening first drive after the rebuild?
There are a lot of possibilities, you didn't mention if you have an engine light on but I would start by checking for codes.
Thread Starter
Heel & Toe
Joined: Jun 2009
Posts: 20
Likes: 0
From: Opelika Alabama
yea im running stock injectors but i also have the fuel pressure regulator turned almost all the way down and no it was running fine for the first month after the rebuild and im just stumped its got all new sensors but the TPS sensor new knock sensor and all im just new to the vette world i have built many 4 cylinder turbo cars just not V8 so yeah all this is new to me see and from what i can tell the cap i got is just a cheap cap from Oreilly Auto and i beleve one of the contacts are loose but i dont see why that would be a problem on when it warms up the guy that i bought it from took out the console with the check engine light so i dont know if its on or not and right now i dont have anyone to read OBD1 
And other than the little stumble she runs like a scalded ape i mean i can burn the tires 1-3 and its the 4+3 its quick i love it....The idle is good at 1st then it just bogs down up then down up then down that sounds like the TPS but still not sure..It does not do it when i am accelerating just when im going down the road normal
And other than the little stumble she runs like a scalded ape i mean i can burn the tires 1-3 and its the 4+3 its quick i love it....The idle is good at 1st then it just bogs down up then down up then down that sounds like the TPS but still not sure..It does not do it when i am accelerating just when im going down the road normal
Last edited by greddyrcng; Jun 4, 2009 at 10:53 PM.
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Melting Slicks
Joined: May 2001
Posts: 3,270
Likes: 26
From: Winchester VA
Cruise-In V Veteran
Is the Mass Air Flow sensor new? I'm guessing your turbo cars (I thought there was something to the "greddy" in your username) used MAP sensors.
If you check for codes, it will give you the guidance you need. Of course if you have the check engine light missing I think you might have to visit a shop with a diag tool. On these cars, you get the code by counting a series of check engine light flashes.
If you check for codes, it will give you the guidance you need. Of course if you have the check engine light missing I think you might have to visit a shop with a diag tool. On these cars, you get the code by counting a series of check engine light flashes.
Drifting
Joined: May 2006
Posts: 1,428
Likes: 7
From: Chewelah Wa
If the idle is hunting around, that is a sure sign of some kind of vacuum leak. Spray around the manifold with starting fluid or carb cleaner and you will know in a hurry if you have one. Be sure to do it when it is running poorly after it has warmed up.
Team Owner
Joined: Feb 2006
Posts: 24,460
Likes: 7
From: sw Ohio
One way to test the MAF is to unplug it and then start the car, if symptoms improve then you've found the problem. However, since this doesnt occur until the car is warmed up I doubt this is the problem.
As far as fuel is concerned it should be around 33-35 psi as '85s run a lower stock fuel pressure. The original injectors could be failing but again there is a way to test them. Ohm the injectors themselves and they should all be at/or close to 16 ohms. Anything more than a few off should be replaced.
You still havent told us if you've checked for codes. Jump terminals A and B on the ALDL connector under the driver side dash and turn the ignition to on. The Check Engine light will start flashing. The first thing you will see is 1 flash, then 2 flashes. This is a Code 12 which is normal. Codes flash 3 times and then change if there are more present.
As far as fuel is concerned it should be around 33-35 psi as '85s run a lower stock fuel pressure. The original injectors could be failing but again there is a way to test them. Ohm the injectors themselves and they should all be at/or close to 16 ohms. Anything more than a few off should be replaced.
You still havent told us if you've checked for codes. Jump terminals A and B on the ALDL connector under the driver side dash and turn the ignition to on. The Check Engine light will start flashing. The first thing you will see is 1 flash, then 2 flashes. This is a Code 12 which is normal. Codes flash 3 times and then change if there are more present.
Last edited by Demonic85; Jun 5, 2009 at 01:58 PM.
Racer
Joined: Sep 2004
Posts: 495
Likes: 0
From: berwick pennsylvania
with all your engine mods i would imagine your running long tube headers . I had the same kinda problem when i put in my 383. i would go in and out of closed loop and then load up the plugs then they would clean out. i had to use a heated o2 sensor and play with the heat range on the plugs in my case.
Team Owner
Joined: Feb 2006
Posts: 24,460
Likes: 7
From: sw Ohio
Race Director
Joined: Aug 2000
Posts: 14,130
Likes: 7
Cruise-In II Veteran
If you have a incorrectly adjusted TB minimum air set screw and incorrect adjusted TPS,you can get a hunting idle from that too.
You may need a scanner to see that.If the IAC counts are 5 and go to 0,its not adjusted correctly.I had a similar problem.After I reset the minimum air and tps the hunting idle went away.
I found sometimes the factory setting for it doesnt always work with mods.You may have to cheat and increase the min air a little bit and see if that makes a difference.Maybe increase it by 100 rpms or so.
I did that until I got a chip with the correct specs to run right.I raised it a bit and it fixed a hunting idle at idle speeds and made it more driveable.
You may need a scanner to see that.If the IAC counts are 5 and go to 0,its not adjusted correctly.I had a similar problem.After I reset the minimum air and tps the hunting idle went away.
I found sometimes the factory setting for it doesnt always work with mods.You may have to cheat and increase the min air a little bit and see if that makes a difference.Maybe increase it by 100 rpms or so.
I did that until I got a chip with the correct specs to run right.I raised it a bit and it fixed a hunting idle at idle speeds and made it more driveable.
Thread Starter
Heel & Toe
Joined: Jun 2009
Posts: 20
Likes: 0
From: Opelika Alabama
well i think i found alot of the problem when the guy put the motor back in he left a lot of the vacc un hooked like the Fuel Pressure Regulator to the Idle Air Control Valve he tryed to bypass it alot of it it just set up to circulate and not run thru the proper channels...