I have a '93 Z28 that I have a couple lights on the dash that are on that I'm trying to fix. Any help or ideas would be appreciated .

First, there is the fluid level light. I have already figured this one out I'm pretty sure. The coolant sensor is bad I think because when i disconnected it the light turned off. So i need a new one of those. How much are those and where could I get one?

Second, the seatbelt light is always on. I looked around the seat and found a plug near the base of the seatbelt that was unplugged, so I plugged it back in hoping it would be as simple as that. But it is still on. I'm not sure what to try next?

Third and lastly, I have a Check engine light on sometimes. It doesn't come on every time that I drive it, but most of the time it does. Something i noticed tonight is either I'm imagining things, or it appears to turn on about a second after the fans start up (another strange thing is the car never warms up past the the first big tick mark on the temp gauge. The last owner trying replacing the thermostat with a replacement stock one, but it didn't help). I checked the code that it is throwing a couple weeks ago and it is DTC 26. This is an explanation of it, but I have no idea what it really means:http://www.fastbird93.com/diagnostics/dtc26p1.jpg

What do you think?

 

I looked at another site and this is what it says about DTC 26:
"Evaporative Emission (EVAP) canister purge solenoid valve circuit" and it says for '93 only "Quad-Driver Module (QDM) #1 circuit
applies to:
- AIR pump relay circuit
- EGR solenoid
- EVAP solenoid"

 

NEW PROBLEM!

I just went out and tried to go home, but couldn't (from my apartment at school). I started it and it ran fine for like 20 seconds while I waited for a car to go by before I started backing out, and then when I was backing out of the spot it died! No sputtering or anything, just plain died instantly. so I put it in neutral and rolled back into my spot and tried starting it. It runs starts just fine and runs fine for like 2 or 3 seconds (maybe a bit more) and then it just falls to zero rpm and dies. I tried holding my foot down a little on the gas, and that keeps it running, but after that couple seconds at the beginning it starts surging badly over and over (right when it would normally die). I hold it at about 2000rpm and it falls to 1000 and back up over and over. What's going on?? It seems like a fuel thing maybe. I really have no idea though...

 

The best advice myself, or anyone else on this board could give you is simple:

1. remove the radiator cap. (do this after engine has cooled)

2. remove rolling chassis from beneath current radiator caps vicinity (do this at the top of a hill, preferably with a clear shot to a large pond or lake at the bottom of said hill)

3. slide new chassis, complete with engine and body under radiator cap. ( a clean, clear title is highly advisable)

4. secure radiator cap to new automobile and be on your way. (stop busting you knuckles on an old POS)




bottom line, the car is 15 years old.

it has seen better days.

stop throwing good money after bad.

good luck.

 

Haha, funny funny. lol. I told like three people about that comment .

I happen to be a college student and can't just go out and buy a new Z51 corvette like I see someone else has... So first off, I do have a nicer car, and this is just my cheap little daily driver so I don't put tons of miles on my other one and I can keep it nice. I have spent $2050 on this car so far, including buying it, and absolutely nothing on fixing it. So far they have all been very small fixes that haven't required anything but an adjustment or something. Other than a couple lights on the dash and a little bit more loose steering wheel the thing drives just as well as my '00 WS6 with 26k miles on it. It's not like this thing is or anything, so far it has just needed some adjustments and plugs plugged back in, and now it sounds like something cleaned, and it will be fine. I have been very pleased with it so far and after these little things are finished I will be buying some tires for it, and it will be a very nice daily driver.

Anyway, back on topic. Someone suggested the IAC valve as being the possible cause of the surging/dying. The only thing that doesn't make sense to me about that I can hold the gas down part way and it still almost dies. So it surges down from where it should be, not up, like I would think a valve stuck open or something would cause. I know nothing about them though, so I really have no idea. What do you think?

I'm planning on cleaning everything out this weekend, because I may have already solved(or almost solved) two of my problems with one little 5 minute thing I did. I noticed on those other sites that it says the EVAP system is another thing that can cause the DTC 26 code, and that they still say it is an electrical/voltage problem, so I looked up where the EVAP system was. I found out where it was and where the plug was for it and looked at it. When I pulled it out, what do you know, one side of it was all gunked up. So I went and got a pencil and a paper towel (best I could find to clean it out at the time) to try cleaning it out a little. It didn't do a very good job, but I could see a difference. I plugged it back in and started it, and it ran for probably 25 minutes without an engine light and it actually got up to temperature for the first time for a long time. During that amount of time I pulled the plug out a couple times to see what would happen, and both times I pulled it out about 20 seconds later the fans would kick on and the engine light would come on. Other than that the light and fans never came on (except when they needed to cool it down when it got to like 210 deg.). It also didn't surge anymore, but I don't know if thats just a coincidence or not... Anyway, I drove it all the way home tonight (about half an hour) and it drove just fine the whole time with no engine lights at all or surging as far as I could tell. So this weekend I am going to give it a good cleaning in all of the plugs and the valves like the IAC valve and stuff like that. Hopefully all will be better after that .

 

A year later and I'm just now trying to figure out what the DTC 26 really is.... lol. It's not the EVAP solenoid up by the engine, I know that for sure. Any ideas on how I can diagnose which part specifically it is?

 

Did you figure out what the surging problem was? Or is this still a part of that problem?

 

Since you have money, we're all glad that you're willing to send us some money so we can buy a better car! Thank you for this generosity!!

Now, while I applaud your wit, I offer demerits for your lack of help.



The sensor isn't hard to replace in the radiator, so I won't go into that (not the coolant sensor in the water pump though)

EVAP solenoid is something you can replace, unplug, or possibly tune out (I haven't figure out the tune out part as I tried)

Seatbelt light is a switch in the latch that triggers the light on or off. It's an idiot light and only way to fix that is: Pull the bulb, replace the switch (if possible) or jumping the wires together should complete the circuit and turn the light off itself (I can't be held responsible if that somehow shorts something out though!!)

As for your new problem, I really don't know. I'd start checking the obvious culprits: Fuel and Spark. Pull the wire off the coil and see if a spark jumps between the coil and wire, if so then move to a plug and do the same. If no spark from wire to plug then go down and check wire to cap. If no spark there then you need to replace your Opti, you have my condolences and sympathy! If there IS spark, time to check fuel! See if when you turn the car on if it gets over 40PSI and HOLDS that pressure. If it doesn't hold it then you have a leaky injector, and depending on how fast it drops, you could have multiple leaky ones. If it gets too much pressure (over 50psi) then I'd say your regulator is shot. If it doesn't get enough, could still be the regulator but also could be the pump going out OR a plugged filter. Bad regulators usually leak fuel (but not always), so do a visual and touch check on the regulator (back of the intake).

That's all I can think of, GL.

 

Code 26 is very common on the 93s and normally caused by the air pump. Pretty rare for the other parts of the system to fail. When you start the car you should hear the air pump running. If it doesn't it will throw a code 26.

Either the pump is bad, or common on 93s is the power wire shorted out.

Typically they fail:

The pump is old and it just died.

Over time the check valves on the exhaust go bad and allow exhaust to flow back into the pump, this eventually kills the pump, often during the winter this condensation settles in the pump, freezes, then when you start the car the pump burns out.

There is a wire that runs from the fusebox ( under the hood) to the pump is to thin a gauge and burns out. The factory used a thicker gauge on later years. Look at the harness ( I think it's a white wire ), test it for voltage, you might just need to run a new 12 gauge wire if you want to keep the pump.

I'm 99% sure you can just unplug the pump and if that is the problem the code 26 should go away.

The stalling issue is going to be a bit harder. When it stalls, check if you have fuel pressure. There is a test port ( shrader valve ) on the fuel rail where the fuel lines connect to the fuel rails, take the cap off, put a gas over it and depress the valve and see if you have fuel pressure. Could be something as simple as a clogged fuel filter. Also check the coil wire, and then tend to corrode over time.

 

If you still haven't found out what your problem is, you might want to look at some other boards that are geared more towards the LT1, ie camaroz28.com, ltxtech.com, second, if you have a laptop and you don't mind spending $90, I'd say go out and purchase the usb to OBDI cable and download some free software and see what exactly is happening just before the car dies. Hopefully some of this will help you out.

 

You can just remove all the AIR and EGR stuff as long as you leave the EGR Solenoid plugged in. Just cap off all vacuum lines. The big 3/4" hoses I just plugged up with whatever was big enough and then hose clamped around it. Later I then removed the manifold plugs and welded a bolt in them. So I'm emissions free under the hood.

 

Thanks for all the help guys. I guess I should have specified.... The only problem I'm still having is the DTC 26.

And this is what I've figured out so far. It isn't the EVAP solenoid, I figure that out last round.... When plugged in, the AIR pump blows the fuse for it under the hood. When it's unplugged I still get the code (I disconnected the battery for a while and everything to reset the ECM). And when I put a jumper wire between the connection E1 and E4 on the fuse box, the pump does not turn on like my Haynes manual says it should.

Thanks again for the help.

 

Is AIR pump unplugged WITH a good fuse in it? Try hot wiring the pump with just wires from the battery to rule out a wiring problem between fuse box and pump...

 

Yes, the AIR pump was unplugged with a good fuse. Light still came on... :\

So... get down in there to the pump and get wires stuck into the plug somehow? That might be tight... lol. Maybe I can take the pump out to test it. Hmm....

Is there any negative effects of this at all? If I *don't* fix it, is there any problem with that?

 

on your seatbelt!!! the light wont go away by just plugging the plug in... but it shoulg go away when you PLUG YOUR SEATBELT IN THE BUCKLE!!! BTW im not too far from you...you bring it out i could hook up the scanner and we could go through the codes and try to figure some stuff out...got a snapon troubleshooter so we should be able to figure stuff out

 

lol, the seatbelt is plugged in .

Thanks, but it's a '93 and those use different computers than the rest of the years you know, right? I know exactly what the code is because you just have to jump a plug under the dash and it gives you the code.

 

Even his scanner should read it for you, and maybe more accurately, but I can't say for sure.

As for the hot wiring the pump, I actually implied removing it heh I keep forgetting they're bolted in Mine, whoever did it, probably had it removed at one point in time, and it was just zip tied up under the motor

 

lol well glad to hear it was plugged in haha...this scanner is like pretty much the best of the best out there!! yes it will run the codes and tell you how to fix it and where to look...its up to you man...just come out and i will run them, i love workin on these cars and never have worked on a speed density car so i want to learn some more about them....bring her out if you want to

 

Oh ok, I figured with a different plug, and being able to jump it to get the code, that a scanner for other years wouldn't work with it. I should just stop trying to think . haha

Haha, wow. Yeah, mine is bolted in there nice and tight. To the frame too since it's a '93...

Alright, well maybe I'll take you up on that. Right now I'm kinda busy with school, but I'll let you know if I get free and want to check it out. And thanks btw

 

I have a working air pump from my 93 Z the "fell off" along with all the other hoses and chit. If you need the pump just PM me and its yours for the cost of shipping.