Fuel additives

[32valvZ]

Originally Posted by lfalzarano

But the LT5 is still as strong as she was at 6K miles when I bought it. Although I believe that the Ethanol has caused problem on many members Z’s, my old daily driver (stock except for Marc’s Chip) is still an awesome drive.

What are the signs of failing injectors, if I still get throw back in my seat at WOT?


Lou

Having had the car that long, for that many miles... you wouldn't notice degradation because its gradual. You might be surprised what new or reman injectors feel like.... Is your idle as smooth as it should be? Any kind of stumble?

[lfalzarano]

Idle is smooth and perfect, and no stumble with fresh gas! [emoji28] It is possible that one of the two prior owners had them swapped out. I didn’t get any maintenance records from the prior owners who only put on 6K miles in their 10 years of ownership. If it has gradually slowed down then it’s keeping up with my slow down at 70... [emoji23] I don’t notice it.


Lou

[Z51JEFF]

Originally Posted by JMO343

I know. I don't think injectors were ever done on my car. So I would think I am due. 1990 car with 5,000 miles on it. When do you start to have issues with them??

John
1990 #2331

My car had 8000 miles when the injectors died. You will do it sooner or later. Do you work on your car?

[Paul Workman]

Originally Posted by lfalzarano

My car has 84,000 miles. I lost one 18 years ago to a backfire during startup. I now make sure I never turn the key off until the engine fires up. I am changing to 91 octane Ethanol free unleaded to avoid the potential injector failure. So far I have been lucky. I do put Stabil Storage gas treatment on each tankful to keep the gas fresh, since my ZR-1 is retired like me.


Lou

84k miles with ethanol laden fuel with no affect to original injectors is WAY outside the "bell curve" (statistics) norms! That alone is worth investigating - if nothing else but to satisfy curiosity!

E.g., could the OE injectors been changed before you got the car? Was the fuel purchased always ethanol laden? Did in fact Sta-bil have an effect on the dissolving of the injector's internal coil insulation? Or, have the OE injectors in fact suffered the effects of alcohol and you're just not experiencing it?*

*Note: Let me share something w/ anyone thinking they can "pooh-pooh" replacing their OE (Multi-tec) 90-92 OE injectors (or do so selectively):

The OE injectors in my 1990 were replaced with NOS injectors at 37K miles. Somewhere under 8000 miles (no telling exactly when) the injectors had begun to fail. But, up to the point of less than half that many miles, there was no "seat of the pants" issues (or so I thought), but there was only a slight knocking of the dual mass FW when idling, which at the time I thought was "normal"...NOT!

The first indication there was something wrong was my first dyno session. The dyno operator cut the pulls off early b/c the AFR was going too lean near the top end of the RPM range. NEVER ASSUME. But, that was exactly what I did - I ASSUMED that b/c the injectors had been changed a year ago (under 3000 miles drive) that the lean situation had to do with the tune instead of the injectors. That assumption was costly, as it turned out.

A couple years later, after I had installed headers and done top-end porting, I discovered what turned out to be a burnt valve. But, as long as I had the heads off to fix the valve issue, I finished my porting project (the heads), and then sent the car to Marc Haibeck for dyno tuning. That's when Marc discovered the problem with the injectors. Same thing happened as my first dyno pull a couple years before: AFR going dangerously lean above 6k rpm, and no adjustment to the fuel tables had any effect. Bad injectors, was the diagnosis.

Upon Marc's recommendation, I bought a full set of Accel injectors, and when I pulled the plenum, SURPRISE-SURPRISE! The GM dealer's shop that replaced the injectors at the time of purchase (by me), replaced them from old stock - the OE Multitecs which were susceptible to alcohol!

So, I guess my reason for dragging you through all this saga was to point out how insidious the issue with alcohol presence can be - especially to the seat of the "seat of the pants" monitor!

Epilogue: Before replacing the injectors with the Accels, I took resistance readings on all 16 injectors. IIRC, most of them read 10 Ω or less, and in particular, the cylinder with the burnt valve read only about 6 Ω! Looking back at that first dyno pull, had I not assumed "it CAN'T BE THE INJECTORS - they were just replaced," Had I checked them instead of ASSUMING, I might have prevented later burning a valve. And, oh-by-the-way, from the perception from the driver's seat, at WOT it seemed to run well. Little did I know that (in ONE cylinder especially) it was running very lean and likely the reason for destroying the valve.

*If anyone is interested, I can dig up the procedure and injector relay(s) connector pin-out info. With that you don't have to pull the plenum to read the resistance - you can do it external of the plenum.

The attachment shows the first dyno pulls that indicate trouble brewing which had gone unnoticed from the drivers seat, up until then. (only a little (over-looked) knocking of the dual mass FW when idling was present. And, BTW, after installing the new injectors, that knocking went away and the idle was never smoother!)

[lfalzarano]

Paul,

Thanks for that information. Can PM the procedure or post it somewhere. To your point it is possible that one of the two prior owners had them replaced, but when I purchased the car in 2000, there were no maintenance records provided.

Again, thanks for providing your personal experience and knowledge to the potential problem. Yes I drive by the seat of my pants, but after driving it daily for 78,000 miles, I can immediately tell if something is different than yesterday. But to your point, it might not be noticeable but a gradual fall off in performance or a drastic burnt valve.


Lou

[lfalzarano]

I did some research on preventing ethanol damage to engines.

1. Purchasing gas from busy gas stations and being able to replace it every 2 - 3 weeks is the best preventative measures you can take to avoid unnecessary E10 Ethanol problems. (Drove mine everyday and tanked up from almost half full every 10 days)

2. Ethanol isn’t a problem for cars and trucks that are used daily, especially if you use an ethanol additive, treatment or a fuel stabilizer at every fill up to remove water and keep gas fresh. (Drove my Z daily but didn’t use a gas treatment)

It’s another story when it comes to ethanol treatment for the fuel systems in engines that sits idle for long periods of time. (The ZR-1 sits for long periods the last 3+ years, but I add Stabil Storage to the tank each fill up approximately 3 times per year.)

3. Keep the tank as full as possible.

Moisture condenses in the empty space in the tank, so reducing the amount of air decreases the effects. Top off the tank to 95% full (to allow for expansion and minimize explosive vapors) and use a gas treatment or fuel stabilizer. (Don’t fill up the neck of the gas tank.)

4. Use an ethanol treatment or fuel additive.

These products like Stabil are designed to help offset the effects of moisture in today’s ethanol blended fuels.

Note: I’ve inserted my operating experience in owning a 1990 ZR-1. I tried not to go below half full to avoid water accumulation and to always use fresh gas from a busy gas station.

JMHO and I am not saying I’m an expert on Ethanol gas either. I’m just trying to understand why so many of you are replacing your injectors.


Lou

[Paul Workman]

Originally Posted by lfalzarano

I did some research on preventing ethanol damage to engines.

1. Purchasing gas from busy gas stations and being able to replace it every 2 - 3 weeks is the best preventative measures you can take to avoid unnecessary E10 Ethanol problems. (Drove mine everyday and tanked up from almost half full every 10 days)

2. Ethanol isn’t a problem for cars and trucks that are used daily, especially if you use an ethanol additive, treatment or a fuel stabilizer at every fill up to remove water and keep gas fresh. (Drove my Z daily but didn’t use a gas treatment)

It’s another story when it comes to ethanol treatment for the fuel systems in engines that sits idle for long periods of time. (The ZR-1 sits for long periods the last 3+ years, but I add Stabil Storage to the tank each fill up approximately 3 times per year.)

3. Keep the tank as full as possible.

Moisture condenses in the empty space in the tank, so reducing the amount of air decreases the effects. Top off the tank to 95% full (to allow for expansion and minimize explosive vapors) and use a gas treatment or fuel stabilizer. (Don’t fill up the neck of the gas tank.)

4. Use an ethanol treatment or fuel additive.

These products like Stabil are designed to help offset the effects of moisture in today’s ethanol blended fuels.

Note: I’ve inserted my operating experience in owning a 1990 ZR-1. I tried not to go below half full to avoid water accumulation and to always use fresh gas from a busy gas station.

JMHO and I am not saying I’m an expert on Ethanol gas either. I’m just trying to understand why so many of you are replacing your injectors.


Lou

The issue with alcohol and the stock 90-92 OE injectors is NOT water resulting from alcohol, but the result of the wire windings of the coils immersed in a chemical acting as a solvent on the insulation of the coils windings. One by one the wire become exposed and with the addition of heat, the wires expand and come in contact with each other- thus shorting one to the other. This is why the overall resistance across the entire coil is an indication of the amount of deterioration: the health of the injector(s) themselves.

When the individual coil windings short to one another it is essentially as tho a winding was effectively REMOVED from the coil. The result is less electromagnetic force, force needed to operate the injectors pintles (i.e., think "valve"). As more and more of the insulation is dissolved and more wire coils become shorted, the leas electromagnetic force is acting on the pintles and the less fuel gets passes through the nozzle. The result is leaning of the AIR/FUEL ratio. Water ALSO resulting from the alcohol is separate matter.

[spork2367]

Originally Posted by Paul Workman

The issue with alcohol and the stock 90-92 OE injectors is NOT water resulting from alcohol, but the result of the wire windings of the coils emmersed in a chemical acting as a solvent on the insulation of the coils windings. One by one the wire wire become exposed and with the addition of heat, the wires expand and come in contact with each other- thus shorting one to the other. This is why the overall resistance across the entire coil is an indication of the amount of deterioration: the health of the injector(s) themselves.

When the individual coil windings short to one another it is essentially as tho a winding was effectively REMOVED from the coil. The result is less electromotive force, force needed to operate the injectors pintles (valve). As more and more of the insulation is dissolved and more wire coils become shorted, the leas electromagnetic force is acting on the pintles and the less fuel gets passes through the nozzle and the result is leaning of the AIR/FUEL ratio. Water ALSO resulting from the alcohol is separate matter.

Beat me to it.


The issue that additives are made for is to counter the hydroscopic nature of alcohol which is the mechanism by which it sucks moisture out of the air.

The second issue is the issue of compatibility with rubbers and plastics. There is no solution for that (no pun intended). Eventually, no matter whether the vehicle sits or not, the ethanol will eat through things it's not compatible with.

The mixed issue is that in carbureted engines and in metal gas tanks, when the water collects, it sits at the bottom and can rust gas tanks and eat away at the zinc chromate, then die cast parts of a carb. So that isn't the ethanol itself.

[Hib Halverson]

In the late 90's, I did quite a bit of research on Delco "Multec" injectors.

As Paul says above, with the early design, used from 90-92 on ZR-1, and as far back as 87 on other platforms, ethanol oxygenated fuel attacks the coating material on the coils. That eventually causes an electrical failure.

There is a second problem with E10 gas that affects all the Multec's regardless of model year and that's rust. Multecs were made with steel internals.

E10 gas is hygroscopic. With vehicles that sit unused for long periods of time–"long period" defined as one really long time or a series of long but not "really long" periods–with moisture-laden ethanol inside injectors, the steel parts inside them will rust. Once enough rust is accumulated such that "flecks" of rust can break loose from these internal parts and get carried away by fuel flow, if the flecks are big enough to block the injector discharge holes, then you get a partially clogged or clogged injector.

Once there is rust build up inside the injector it is impossible to fix...even with ultrasonic cleaning because 1) you can't stop the rust and 2) ultrasonic cleaning cannot remove the rust.

For this reason back about 1997, I installed a set of RC Engineering rotating disc type injectors which had all stainless-steel internal parts. Another benifit of RCs is the better performance of the rotating disc design over the Multec ball-and-socket design.

I still have the set of OE injectors which were in Barney, the '95 I used to own. It includes four which the late Russ Collins (the "RC" of RC Engineering) and I cut apart on his lathe to view the rusted internals. With a magnifier, I could see flecks of rust which had blocked the injector discharge holes.

That set of 16 RC Engineering injectors was in the car's LT5 when I sold it to (a person) in Florida back in 2016 and are still in it now.

At this point in time, 28-30 years since ZR-1s with the early Multec injectors were manufactured, I can't believe anyone is still talking about testing, much less, using those old injectors or screwing around trying to find pour-in additives to address problems caused by ethanol.

WTF?

You guys should have all switched to RC Engineering injectors or some other brand of injectors with stainless internals.

[precast1]

Does anyone mix fuel I can get 89 octane unleaded ethanol free at the gas station down the street. I then mix it with 104 octane unleaded ethanol free from a speed shop. My 1990 car just turned 1000 miles. When we changed all the fluids we check the gas tank no rust. Car runs great. Is this a fix to the problem or not. Had a 90 about 15 years ago so just getting back into it. Should I change the injectors anyway and if so Arron Scott with SGC is the only one I know that is somewhat close. I live in Central Florida.

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