CorvetteMusic

Long time lover of the forum, but haven't posted anything in many years. I have an 88 Corvette that has always run like a top since I bought it, however, I live in Colorado and they have increased the emission requirements on my Vette to the point where I have been unable to pass emissions despite trying most everything in the book at a great cost of time and money.

Finally out of desperation I put half a gallon of denatured alcohol in about 10 gallons of gas. The car ran perfectly and passed emissions. I immediately went to the gas station and put 85 octane gas in the tank and filled it up. I then drove it for a few hours and burned off about half of that and then filled the tank again with 91 octane fuel. My Vette ran fine the next four or five times I drove it, even though I did not put a lot of mileage on it. Today I went to get it out for a drive and the idle was bouncing all over creation and if I didn't give it a lot of throttle it would always die. The engine was also making a somewhat regular popping sound, not real loud, but I could feel it through the accelerator, like someone poking the bottom of my feet. I am fearing the worst now that the denatured alcohol has done significant damage to my fuel system. My Vette has never run like that in the 13 years I have owned it. The Service Engine soon light has not come on, nor have any other alerts. There are no leaks anywhere of fuel that I can find, although it does seem to be spewing more exhaust and the smell is a bit stronger/blacker than what I am used to.

Sorry for the long explanation, the two questions I have are;

1. Could this be unrelated to the denatured alcohol, and if so, what are your thoughts on what might be going on?

2. If it is the denatured alochol, how nasty a repair bill am I likely looking at to fix it?

I have already called a local shop, Corvette City, and am planning on having the Vette towed there next week. Any suggestions or ideas on what could be causing the problem and the likely ballpark cost to repair would be immensely appreciated.

John A. Marker

I think your problem is something unrelated to the use of the alcohol. I have used it several times in the past on my Vette and other cars without a problem. The use was recommended by a friend that works on high powered Corvettes for a living. When I have used it in the past, I used one (1) gallon to about 5-7 gallons of gas in the tank. Your ratio is even more diluted. I just can't see this as creating the issue with your car. If you were having trouble passing SMOG to begin with, there are other issues.

Have you pulled any codes stored in the computer? I would suspect a O2 sensor as a likely place to look. Next I would look at plugs, plug wires and see if the injectors are all firing.

When you filled the tank after passing....why didn't you just use 91 to begin with?

CorvetteMusic

John, thank you for the prompt feedback, it is much appreciated.

I put the 85 octane gas in out of fear the octane level had been boosted way too high using the denatured alcohol. I was trying to bring it back down in to the range of normalcy. I am no science whiz, so this may have actually caused the problems I am experiencing?

After I filled the tank with the E85 I drove the car a good 150 miles and it ran like a top, no issues with knock or idle problems. After putting in the 91 octane gas I probably drove it another 5 times for a total of 50 or 60 miles without an issue.

I don't have access to a code reader, so I am at the mercy of a local garage with the reader.

I am encouraged that you don't think the denatured alcohol is the problem. I am still concerned because I have never had my Vette idle like that or make that poppind sound. The spark plugs, wires and injectors were all replaced about 5 years ago and have only seen about 3,000 miles of use, so I am worried that may not be the problem. Could a bad 02 sensor cause the issues I am experiencing?

Thanks again for the feedback John!!!

John A. Marker

I believe that your 88 codes can be read with the paper clip method without getting a code reader. With the car off, you can put a paper clip in terminals A & B (top two terminals to the very right of your ALCL under the dash next to your right knee.

You open the paper clip so it forms a "U" and insert it into the terminals. Then turn the key to the ON position....don't start the car. Your CHECK ENGINE light should flash once and then twice (code 12) ...this should repeat three times. This is telling you that you are connected to the on board diagnostics. THEN it should blink any stored codes in the computer.. As an example...if it flashes four times then five times (it repeats three times) this is a code 45 indicating RICH EXHAUST. You could have more than one code stored....so write down all the flashes....eventually you will get the code 12 flashing three times indicting that is the end of the stored codes. Turn the key off and remove the paper clip.

If you want to reset the computer (remove all the stored codes), disconnect the negative battery terminal for about 20-30 seconds.

let us know what you find

blackbear bob

Did I read that right? You put E85 in your 88 Vette. E85 is not 85 octane, it is in acually 85 percent ethanol. It is certainally not recommended for non flex fuel vehicles. I would guess you will need at least another set of injectors, as the ethanol is very caustic. Good luck.

JackDidley

E85 will cause your car to run very lean, if thats what you put in it. Ive been using it my 87, 2 1/2 years. It is not caustic.

ghlkal

Although I haven't done it, I know others that have put denatured alcohol in to pass emissions without long-term problems. So I would also think the problems weren't caused by the alcohol.

Originally he said 85 octane ... so hopefully the second post (E85) was in error

Voxego

I'd be scared. I have read that our FIs were not built for ethanol. You running stock injectors?

JackDidley

Bosch IIIs. I also put some old non FI rubber line in a jar of E85 and let it sit. After about a year there was no signs of decomposition, I threw it out.

Benny42

I bet you helped send those injectors to their death. I ran a tank of E85 thru my
'89 Formula to dry out some wet gas... not long after, it needed a set of injectors.
They were going to die anyway, its a matter of time with those things.

Silver96ce

If you replaced your injectors with early style multec injectors, you may have damaged them as they were subject to damage from cleaners and alcohol.

Here is a part from a GM bulletin about injectors:

"Multec I: Pre-1994 Multec I injectors should not be cleaned, and no additives are
recommended. These are wet-coil injectors with deposit-control tips. Multec I injectors built
after 1994 are wet coil injectors with deposit control, but because of internal changes, these
injectors can be cleaned, and an additive can be used to prevent deposit buildup. There is a
GM bulletin with the proper procedures and precautions for cleaning these injectors.

Multec II: Multec II injectors are a dry-coil, deposit control design with several internal changes,
including the use of stainless steel and an increase in core stroke. If deposits build at the tips of
the injectors, there is a cleaning procedure bulletin."

Also check your oxygen sensor. The alcohol may have cleaned a lot of crap out of the engine and damaged it.

CorvetteMusic

Thank you so much to all of you for responding and providing your excellent insight. My apologies for confusing you with the "E85" comment. I put 85 octane in the tank, about 10 gallons of it, to mix with the remaining denatured alcohol and 91 octane gas that was in there prior.

Would bad injectors cause the horrific idle problems and possibly the popping sound I am hearing? Assuming it is my injectors that are shot, any recommendations on what I should replace them with? Living in Colorado I know the gas stations add some ethanol to the gas, particularly in the Winter time to help combat pollution.

I am going to try the paperclip reader suggestion and will let you know what code/s I find. During this entire ordeal I never had the Service Engine light come on, which I found baffling given how rough the car was idling and the black smoke pouring out the exhaust when I really got on the accelerator.

Assuming I am looking at a new set of injectors and an 02 sensor, taking labor in to account, how much money am I soon to part with?

Thanks again to everyone for taking their time to try and help me. One of the greatest reasons to own a Corvette is the incredible community of friends out there always ready to try and help.

gerardvg

I would recommend disconnecting the battery for 10 seconds, the ecm will change things to try compensate if it sees a problem.
I have had my vette running not right, disconnecting the battery and letting the ecm relearn fixed most of the problems.
Good luck

HlhnEast

Before you do this go ahead and read the codes and write them down. Some of them may be old and you have fixed them already. Clear them as Gerard suggests, hopefully it will clear your problem and if it continues then you will have the codes for what is wrong right now.

Good luck with it!

Oh and changing injectors isnt terribly hard if your handy at all. Do a search here or more info, I would think the hardest thing is leaning over the car for a few hours.

Paul Workman

Affect idle?? Oh, hell yeah! And, often will not throw a code, at least initially.

Pre 93 (94?) the coils, or rather the insulation of the wire in the injectors, was (alcohol) soluable. As little as 10% has proven to cause them to fail. So, you adding alcohol may have, as suggested, just hurried up the inevitable! If you measure the resistance across the individual injectors, it should be around 12 to 14Ω (not sure on the L98 injectors), and they should all be within a range of ± an ohm or so across the lot. Also, often is the case where an injector reading will be in the normal range when cold, but when heated (or idling for a short while) the problem appears and the resistance suddenly becomes significantly less.

Jon at FIC, a board sponsor, can fix you up. He sells new and rebuilt injectors, but get new stainless injectors for under $400 (I think - ask Jon).

As for the octane being "too high", high octane rating itself has nothing to do with excessive heating. It needs to be high enough to prevent knock, but once the octane level is sufficient to avoid knock, increasing it will NOT cause problems, except in you wallet. (Leaving performance tuning that would dictate having to use higher octane out ot this discussion - )

However, alcohol has a significantly lower "stoich" level; it carries some of it's own oxygen. So, adding some to the tank w/o changing the gasoline tune will produce a leaner burn - the reason it sometimes works to get over the hump with the emissions tests. But, as far as the 10% ethanol in most gasoline goes, it has a heck of a lot more to do with the agriculture lobby politics than it does any benefit: gas mileage is reduced as alcohol % goes up, and vehicles not designed for it will have problems, e.g., "rotting" out your injectors...for one!


Not uncommon with injector problems. But! if you have a bad injector or two, you can do serious damage to valves or pistons, due to too running too lean on that/those cylinders...Ask me how I know!

You can do the injector labor yourself. And, unless you're getting a code, I wouldn't bother with the O2 sensor - save yourself about $70 each right there in parts alone. So, you're looking at the injectors and gaskets and (some say) about 4 hours and a couple brewskies to do the job. And, it goes faster with a Corvette bro helping you, long as you control his brewskie intake. (Lesson of my past: NEVER let friends set valves after a few brewskies...I'm just sayin!)

Bottom line: I don't think ya hurt it. The OEM injectors were going to give you fits soon anyway. Instal new stainless injectors and never look back!

Good luck!

P.

Voxego

Nice job, Paul!

Weck86

With Paul and if you are at all handy with a wrench, changing your injectors is not that hard. On the L98 the most difficult part will be putting the plenum and runners back together. There are (I think) 5 different length bolts holding everything together and they have VERY specific locations. So pay attention and label the bolts as to their locations when you take it apart. There are also "hidden" bolts on the back side of the runners.

I also highly recommend Jon at FIC. I put Bosh IIIs in my 86 and am very pleased. Good luck, you can do it, just take your time and don't be in a hurry.

Magyver97

rrt898

I would have to say the same....Multi-tech injectors are not designed for ethanol. That's why most people have to change them because of the ethanol content destroys the injector. If you determine you have an injector problem talk to John at FIC. He will guide you in the right direction. I changed my injectors to Bosch III's.

good luck

CorvetteMusic

So, after putting off the inevitable a few weeks I used the paperclip idea John Marker gave me and discovered a code 34, or MAF problem. I took my modified MAF out (heat sinks gone, screening gone) expecting to see the wires damaged or gone. Nope. Looked perfect from what I could tell. I guess the power and/or burnoff relays could be bad, but could I get that lucky? Anyway, had my baby towed to the shop and should know more in the next few days. Called and spoke with John at Fuel Injector Connection and he was very helpful. If I do have to replace my injectors, I know now exactly what I am getting and the cost.

In the backdrop to all my "problems" is the fire South of me in Colorado Springs. I want to wish all those fighting the fires the best. My heart is breaking for those who have lost their homes. I am truly blessed and it helps put my issues in perspective.