Has anyone noticed gas is BAD lately?

[Sato]

I just finished putting in a new head gasket. I think I got a bad load of gas.{pump premium] After filling it up it started to detonate and I think it hurt the gasket. After the repair I ran a load of Techcron injector cleaner and finnished off the tank [gently] . I then filled it with 93 octane Mobil and still found some detonation although not as bad and had to back off timing 5 degrees even after uping fuel pressure. I run the 1S system with a 1mm jet that turns on at 8 psi boost. I use water/methanol 50/50 mix.
I did move the injection nozzle closer to the intercooler by about 5 inches.
I have checked the WI and it seems to work fine. I just wanted to know if any of you guys in the states have noticed that gas is real bad these days or is it just a problem with my setup.
Thanks,
Sato

[Sato]

But doi I need more water meth to combat this? Am I at my limit with the 1s system with the 1mm jet or is there a problem with the system?
If so so how do I determine there is a problem?
Sato

[hotrod]

There are two or three issues you may be dealing with.

1. There are seasonal changes in the gasoline blends, each major metropolitan area changes from winter to summer blends at different times due to local climate. There are also changes due to the seasonal requirements for oxygenates in some areas to control winter emissions.

2. The detonation sensitivity will go up as summer temperatures peak. If you set up your system during cool weather, you may have to turn up the injection rate or pull back timing a bit when it gets very hot. Once you get a tune that works in very warm weather you should not have to change its settings much except in very cold weather you might be able to either turn it off, or cut back the injection rates.

3. Due to the recent high gasoline prices the refineries may be adjusting the fuel blends to keep costs down. They are required by law to hit an average R+M/2 octane rating as posted on the pumps but they have some latitude in how far apart the Ron and Mon numbers are while still hitting the advertised AKI. High compression high performance engines and supercharged, turbocharged engines are more sensitive to the Motor Octane Number, so if they increased the difference between the Ron and Mon to use cheaper blending stocks it might show up in high performance engines but be perfectly acceptable in your average car.

You may want to experiment with a different brand, of fuel, they each blend a little differently.

Larry

[Sato]

There are two or three issues you may be dealing with.

1. There are seasonal changes in the gasoline blends, each major metropolitan area changes from winter to summer blends at different times due to local climate. There are also changes due to the seasonal requirements for oxygenates in some areas to control winter emissions.

2. The detonation sensitivity will go up as summer temperatures peak. If you set up your system during cool weather, you may have to turn up the injection rate or pull back timing a bit when it gets very hot. Once you get a tune that works in very warm weather you should not have to change its settings much except in very cold weather you might be able to either turn it off, or cut back the injection rates.

3. Due to the recent high gasoline prices the refineries may be adjusting the fuel blends to keep costs down. They are required by law to hit an average R+M/2 octane rating as posted on the pumps but they have some latitude in how far apart the Ron and Mon numbers are while still hitting the advertised AKI. High compression high performance engines and supercharged, turbocharged engines are more sensitive to the Motor Octane Number, so if they increased the difference between the Ron and Mon to use cheaper blending stocks it might show up in high performance engines but be perfectly acceptable in your average car.

You may want to experiment with a different brand, of fuel, they each blend a little differently.

Larry


Thanks for the reply Larry, That does make alot of sense. I feel at this point that I'm at the ragged edge of my Aquamist 1S system with a 1mm jet. At 18 to 20 psi boost I am getting det from my computer with 50/50% methanol and distilled water on 93 pump unleaded. I have to pull back 5 degrees from my computer to stop the det. I know that this is a water/alc forum but the reason I say this is because I filled up with 100 octane unleaded race gas and can run my advance up by 5 to 6 degrees and all seems fine with no det. My water injection comes on at 7 psi boost. With the race gas I can turn the water injection off and still no det with the 100 unleaded at a solid 20 psi boost. Anyone have any suggestions? I can't run race gas all the time!


Sato

[hotrod]

Sounds like you've already eliminated the possibility that you have a plugged spray nozzle, or something similar.

Do you have a means to log the car and determine where in the rpm range, and at what boost level, the car is seeing the detonation?

You might try lowering the turn on point a bit, if the spray is starting just a bit late for current conditions that would be one possibility.

Have you tried changing the water methanol mix, more water, or more alcohol to see if that makes a difference, you might try bumping your methanol to 70% and see how that works.

I don't recall off hand what your car configuration is, so a little more info on the engine, and setup would maybe ring a bell with someone.

Have you noticed any changes in engine temperature since the gasket replacement, -- could the engine be running hotter ?? ie thermostat, radiator fans not running etc. etc.

Larry

[Sato]

[quote="hotrod"]Sounds like you've already eliminated the possibility that you have a plugged spray nozzle, or something similar.

Yup I checked that and it seemed fine. I tried moving the water jet further away from the throttlebody and it didn't help so I moved it back because some on the list said the closer to the throttlebody the better det prevention and further back the better intercooling effect.
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Do you have a means to log the car and determine where in the rpm range, and at what boost level, the car is seeing the detonation?

I can run the car in 4rth gear and floor it and because of the load it doesn't det. It's only in 2nd and 3rd ,stabbing the throttle. I feel it's happening in ther lower rpm range . If I baby the throttle It won't happen.

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You might try lowering the turn on point a bit, if the spray is starting just a bit late for current conditions that would be one possibility.


I have it turn on now at around 7 to 8 psi boost. How low do some of you guys activate the WI?
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Have you tried changing the water methanol mix, more water, or more alcohol to see if that makes a difference, you might try bumping your methanol to 70% and see how that works.

I tried pure water with no effect and up to 50/50% methanol with no difference, but if I turn the WI off the computer will show some knock retard no matter how I baby the throttle to get up to high boost. I was also told no more than 50% meth with the Aquamist pump.
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I don't recall off hand what your car configuration is, so a little more info on the engine, and setup would maybe ring a bell with someone.

I own a turbocharged ,interccoled, fuel injected Dodge OMNI made by Carrol Shelby in his plant in Whittier CA in 1986. One of 500 made. It is a 4 cylinder 8 valve engine[135 c, A slant 4 if you will as it's the last engine designed by the engineer that made the slant 6.
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Have you noticed any changes in engine temperature since the gasket replacement, -- could the engine be running hotter ?? ie thermostat, radiator fans not running etc. etc.

The head gasket failure was minor as the temps were wadering slightly more than usual but never hot. These engines are known for gasket problems anyway. So I fixed it and it's back to normal, very cool and doesn't wander at all. But there was no difference in the knock threshold.
Thanks so much Larry for your reply

Sato

[hotrod]

I start my injection at about 8 psi, but I've seen some folks use turn on points down near 5 psi. To some extent it depends on the built in delays in your injection system (how long it takes to start spraying a meaningful amount) and how fast your car builds boost.

Hmmmmm -- Not that familiar with the car (aware of it but never worked on one) -- Does it have standard distributor ignition (sounds like it) ?

Have you checked your distributor cap for cracks cross firing, bad ignition wires etc?

You might try pulling back the base ignition timing just a degree or so more if you can.

On the older iron with distributors you'd get that sort of behavior if the timing advance came in a bit too quick. If it is a conventional distributor, you may be able to find a shop that can put stiffer centrifugal advance springs in there (or lighten the swing weights a bit) to slow down the centrifugal advance a bit so it does not reach full advance as quickly.

Most cars of that and earlier periods had a base ignition timing some where around 10 - 12 degrees advance and then it would rapidly add centrifugal advance as the engine rev'd and it would have all the ignition advance in by about 3500 rpm.

It is much easier to get a car to detonate at low rpm than it is at higher rpm (combustion time is much longer at low rpm). So --- if the centrifugal advance came in too quickly, there would be a place in the advance curve near 3000 - 3500 rpm that you are on the ragged edge of detonation. On a turbocharged car the same effect comes up if you come on to boost too quickly.

Given what I know about your car, those are the things I'd look at:

Pull back the base ignition timing just a couple degrees.
Slow the centrifugal advance by using stiffer springs or lighter swing weights.
Widen your spark plug gap a bit to get a faster burn at low rpm, (check ignition wires etc too).
Change your turbo boost setup so it reaches full boost just a tad slower.

Good Luck.
I'll look around and see if I can find any info on your car.

If anyone knows the in's and out's of those engines it would be the guys down at Gary Donovans Dodge Garage.
http://www.thedodgegarage.com/
http://www.thedodgegarage.com/turbo_shortblock.html

You may want to touch base with them -- by the way read his pages on the plymouth reliant called "Relentless" very fun read. (second click down on the "my rides" in the left side of the page.)

Looking through my motor manual it looks like the distributor up through 1983 at least had the centrifugal advance setup. On the '86 it was electronic distributor ignition, but there is no example of the internals of the distributor so not sure if the above will be any help.

If you've never seen the inside of a conventional construction distributor here's an exploded drawing of a typical one, so you know what I am talking about.

This may not be useful to you, but some of the other folks may find it useful, as the pool of mechanics familiar with the older equipment is rapidly declining.

http://www.gordon-glasgow.org/Images/18.gif

#28 are the swing weights
# 29~32 are the springs that control how fast the swing weights advance the ignition timing at higher rpm's



Larry

[AKWRX]

This may not be useful to you, but some of the other folks may find it useful, as the pool of mechanics familiar with the older equipment is rapidly declining. Larry

From the deep end of the declining pool...it's very good advice.