It is running kind of rought due to sitting up before I got the car. I replaced the sparkplugs and wires along with the cap and rotor. I have also replaced the fuel pump as it was dead when I got it.

Here are the problems when driving if I accelerate hard sometimes it seems like it does not want to shift but once it shifts, it is perfectly fine.

Sometimes when accelerating hard everyonce in a while, not that often though it sounds like it is backfiring then once it does that it goes on like it should..

Last thing it is doing is when stopped at a redlight for a while it has idle surging not a lot but a little, at least I think that is what it is, when sitting there it seems like it trys to move forward but obviously cant because I have the brakes on.

Any suggestions on what I should do would be appreciated, I have completely restored the looks of the car now I just want to get it running the best I can.

EDIT: The delayed shift thing I just figured out some more detail on it when I am accelerating hard and it is delaying the shift/not wanting to, if I take my foot of the pedal for a second and go back to accelerating hard it seems to have shifted and is perfectly fine if that helps at all with the diagnosing of that problem

Thanks, Stephen

 

Does anyone have any suggestions of what I should do?

Any help is appreciated.

 

Before going into more depth regarding your questions, I think that you were on the right track when you replaced the spark plugs, wires, distributor cap, and rotor. Any time that you purchase a previously owned vehicle, it's best to change all the filters and fluids plus those ignition parts that can wear out. This gives you a "baseline" to figure out future maintenance as well as nip any problems associated with clogged filters, low fluid level situations. Since you mentioned that the Vette was sitting for some period of time, as fresh tank of premium gas and Techron Fuel System Cleaner or Red Line's SI-1 fuel system cleaner should rid the fuel system of any residual gums/varnishes and maybe some of your fuel-related gremlins.

Your '89 has a fuel filter underneath the car of the passenger side which is often neglected and can cause serious fuel-delivery problems at idle as well as at full throttle. Definitely change that one out. Same for the filter and fluid in your automatic. Low transmission fluid can cause the type of shifting problem you mentioned. Surging at idle can be caused by a partially block air bleed for the Idle Air Control (IAC) valve. Try using some throttle body cleaner in the mouth of the throttle body to see if that resolves the problem. (I also use CRC's MAF Sensor cleaner in my '89 about once a year just as a precaution.)

You didn't mention whether or not the ECM was throwing any codes. An OBDI-reader could help in that department as well as a used factory service manual to trouble-shoot the code(s).

Once you've "baselined" your Vette, it might eliminate some of your problems, if not, come on back to the forum for help. Good Luck and enjoy your '89!

 

High idle check for vacuum hoses leaking, not connected, tps sensor adjustment as well as timing. Start with the basics for your year and model, be systematic and fix things right the first time.

Recently got my 84 the following is what i've done so far god only knows how long it sat but it was not maintained well, scary but true but it's a good bet on what to expect if there's no prior history on your car.

So far fixed the high idle issues, backfiring, shutting off, hard starts i had, timing related and sensor related.

http://forums.corvetteforum.com/c4-t...er-wobble.html

http://forums.corvetteforum.com/c4-t...ay-wiring.html

 

Hi Kitten, What you describe, as has been said, could be lots of things and a combination of things. Let me suggest you start by pulling the fault codes from the ECM as described here. Any ctored codes will point you,and us, to a reasoned solution to your problems.

http://www.extreme-check-engine-light-codes.com/GM OBD1 Decoder.ht

 

I will not be able to do anything with the car until the weekend but will replace the fuel filter and check transmission fluid to see if it is good hopefully sooner than the weekend. If it is bad I will find out how to change it and replace the filter because I doubt it has been replaced in a long.

I just went out and pulled all stored codes it had it only had 1 stored codes and no recent or current codes. It was a low coolant code which I fixed with a new heater core because the old was leaking a little and within a day or 2 of driving was draining half my coolant.

Also when you say put some throttle body cleaner in the mouth of the throttle body, do you just mean spray a little bit into it with the plastic air tubing off and put it back on and start it? Also for the CRC's MAF Sensor cleaner I am guessing you just spray it into the maf sensor or just read the directions and it will be obvious?

Thank you very much for the help.

EDIT: How exactly do I reset codes the proper way, so that I can test again to make sure that there are no codes for certain.

 

Sadly, I do not have an FSM with the car and the previous owner could not find it, therefore I do not know where any of the vacuum lines are located.

Just wondering how did you fix the backfiring, as you can see from my list of problems, I have a problem with it also that the plugs, wires, cap, and rotor sadly did not fix all the way but did make better.

I am going to buy a PCV valve when I go to the store soon or later and replaces that as it seems really nasty and has oil all over it, so it is probably clogged either partially or fully and it is $6 for a new one so it won't hurt to replace anyway.

 

In my case it was a combination of things the main culprit i believe was the ignition pick up coil which was broken and fell apart in 3 pieces and the ignition control module which tested bad and had no heat transfer compound. ( PO installed ).

Before i replaced anything the idle was as high as 1500 rpm and fluctuated badly, now it's better !!

I used these links to videos to help me set true top dead center

http://www.youtube.com/watch?v=wifTHbb06_I

http://www.youtube.com/watch?v=5a2X9mSSlQY

http://www.youtube.com/watch?v=FHX1yXVyIMg

This one was especially helpful !!!

http://www.youtube.com/watch?v=PD0ZR...eature=related

When i first got my car i was driving at 70 mph on the highway, it backfired so bad the car shut off, had to put it in neutral and restart the car while still at speed, ( could not pull over ) at least it happened on the highway and not at 5000 feet altitude in a light sport plane !!!

It did restart but i got a code for the map sensor, either the back firing destroyed it or it was just old.

Replaced the map sensor ( ac delco )and got a new hose for the map sensor to the intake manifold, and used zip ties to hold the hose in place on both ends ( peace of mind that it won't pull out or that i won't accidentally pull it out working in the engine bay ) but it still back fired at 90 mph and started bucking like a bronco and hunting really bad. ( still does this but no back fire, so could be a fuel pressure/flow issue still checking).

Started as you can see with the ignition system in my thread,

Checked initial or base timing, saw that it was apparently at 6 degrees tdc, thought this was right but i was wrong it wasn't,

So started another thread to get advice members pointed me to checking that the harmonic balancer did not shift, it indeed did shift, only after i got a piston stop and checked it did i confirm what members already knew.

My original timing was 14-15 degrees BTDC add some advance to that and the timing was a hot mess to say the least !!

Re-timed the engine to true top dead center, removed the distributor, changed the pick up coil, ignition control module, ignition coil, cap, rotor, plugs gapped to factory spec of 45 and installed mallory 8mm ignition wires ( not a brand preference just got them free ).

Changed the fuel filter,air filter, air cleaner base gaskets and fuel hoses.

Checked for vacuum leaks which i still have i'm sure ( it's idling a little too high at 700 should be at 600 or 650 ). and plugged those off. ( for now until i replace hoses and follow fsm for correct connection points ).

So now it does NOT backfire despite the fact that it still needs a million things to be done it's starting good, idles good under 1000 cold, 600 in gear hot ( 700 in park or neutral )and has good power ( for an 84 ).

Sorry for the long winded post but it may help get your car running right.

 

kitten, all you do is disconnect the battery, leave it for a couple of minutes then reconnect and the codes are all gone. Be aware you'll also lose all your radio presets and it sets your heater control to Auto so the AC will be running when you start.

 

Try searching the "C4 Parts 4 Sale/Parts Wanted" Forum on this site first, then check eBay. I'm on my 2nd '89 and the FSM has saved me plenty of times in the past. Remember, these Vettes are at least 23-24 years old now.

Good point!!! Always check your base timing and your fuel rail pressure against the factory values (6 degrees BTDC & ~43.5 psi). This can cure a lot of surging/backfire gremlins.

Just remember to tighten the throttle body plastic bellows before you fire up the engine or the extra air slipping in past the MAF will mess up the ECM's attempt to control the idle via the IAC. The MAF cleaner is straight forward. I usually take the MAF off the engine with the air bellows attached. Stand the whole assemble upright with the MAF on top and shoot the cleaner/solvent directly onto the MAF's wires and screens.

 

Vacuum line diagram....WW

 

I also have the idle surging issue while sitting at a stop light. I just figured it was an injector issue? I will try a few of these things and see if that solves my problem. Definatly would be a cheaper solution.

 

Thanks, I will definitely be printing that and checking all my vacuum lines in that area.

Also is that for an 89' and is that a online manual? If so do you know where I can download it? If not that is fine I will just buy a cd one and hope it comes in quickly.

 

I just thought of something that I think happened to a friend.

Is there any possibility that there are any cables attached to the throttle body or anywhere else that is accessible that could be loose or not tightened all the way, which would be causing my delayed shift?

The delayed shift thing I just figured out some more detail on it when I am accelerating hard and it is delaying the shift/not wanting to, if I take my foot of the pedal for a second and go back to accelerating hard it seems to have shifted and is perfectly fine.

 

The first thing I would do if having a shifting problem is to reset the TV cable on the side of the plenum. There are posts on here telling how to reset the cable. This cable sets the shift points for the trans...WW

 

I have looked up how to adjust it and I am kind of confused. I have found probably 3 different ways to do it and not sure what to do now.

Do you think you could possibly give me an explanation of how to do it the correct way?

Thanks, Stephen

 

Can anyone show me how to reset the TV cable the proper way?

Pictures would be appreciated but a good walkthrough is also a lot of help.

Thanks, Stephen

 

how did you fix the shutting off issue

 

The shutting off would happen on the highway, consistently around town or on the highway when i was at 35-90 mph.

Misfire, rough idle, rough running would also happen intermittently.

Correctly timing the engine was the first start, replacing worn ignition pickup coil and module, then plugs cap, coil,rotor.

I believe the map sensor was the initial culprit in the shutting off problem. Replaced it after code appeared, then replaced vacuum hose to it using zip ties on both ends.

TPI cars are of course different but the same things to look at are common, fuel,ignition,sensors.

Got no code when it happened the first few times, then when the back fire happened that's when the code came up.

Then as i went through the ignition system found and continue to find a lot of little cheap things that add up to very expensive repairs if ignored ie: po disconnected knock sensor wire, po grounded the temp switch wire to the fans, po removed the temp switch to fans and just used a plug for the block ( you can follow my other threads to see what i mean ).

If your car starts, idles fine, but shuts off when you put it into gear and won't idle in geear this is a SURE sign of an intake manifold leak, or vacuum leak.

Cheap relatively easy fixes that make you think it's something more complicated or expensive which is why it pays to be patient ( i have zero patience ) and go through all the checks and steps and advice that is offered to slowly but surely eliminate all issues that could cause these symptoms.

 

There is only one correct way.
Depress locking tab , push cable all the way towards the firewall ,release the tab , open throttle fully and cable will ratchet out to correct adjustment
( assuming your cable is nor stretched )

Pics
http://sethirdgen.org/tvcable.htm

some background reading on TV function
http://www.cpttransmission.com/tech_tvcable.htm