So I finally got my car running decent with 19 psi and Methanol injection. . .

Then, last night, I hit the gas. It had been running exceptional, but this time when it came up on boost there was a VERY loud backfire. I limped back home because it obviously wasn't running right.

When I opened the hood, I found:
- hose blown off throttlbe body.
- hose blown off MAF.
- 3 vacuum lines blown off.
- underhood insulation damaged.
- wires blown out of IAT sensor(!)
- plastic radiator support broken(!)

Any ideas how boost or Methanol injection could have led to this?

Thanks,
Mike

 

are you using straight methonol?

That is pretty odd. are you sure you didn't get a lean pop on acceleration that maybe set off the methonol down the intake pipe?

When I had the eaton on my car it had horrible AE problems because boost would come on so fast.. That lean pop when I flashed the gas was so bad it would blow stuff apart like vaccum lines, inake pipe, etc.

 

Actually, the throttle was all the way open and the turbo was probably going past 10 psi or so when it happened, so I don't think it's AE. I am running straight Methanol.

BTW, I do have some off-idle and tip-in AE lean issues (never of this severity, though). I can't seem to find a way to program this out. I believe TunerCAT says this table doesn't exist in the LT1 computers.

Mike

 

my point was maybe it was a lean pop.> What was the AFR when it happend?

 

The wideband shows 13/1, but I don't put any stock in this number since I'm supplementing with Methanol. Over a week ago, I ran it on a Lambda sensor and it showed .75 or so.

 

The wideband display doesn't care if you run methanol. While 100% methanol would require 6.4 to 1 for stoich, the sensor measures lamda. The display is just calibrated for a specific fuel based on lamda for your brain to process. You can mix all you want and still tune to a familiar afr on your display. In other words if you are targeting 12.6 afr (on gasoline), you can run diesel, propane, methanol or jack daniels and still tune to that number without worrying about it.

You had a lean hiccup, how is the methanol injection handled exactly? Plumbing, pump, regulation, nozzle, etc...

 

How is the alky injected? a little as the boost comes up or one big hit at 10lbs??

 

I have the alkycontrol.com kit. I inject straight Methanol through 2 - M15 nozzles right in front of the throttle body. I'm using his progressive controller, which activates at 12 psi, then ramps up with boost beyond that.

Mike

 

Can you activate the system briefly to test it with the engine off? Alcohol doesn't vaporize as easily as gasoline and the spray could be impinging on part of your intake system. Hot airflow will help a great deal but there could still be some problems. You also might have picked up some air in the system. The farther upstream you can put the system the better the cooling effects will be. You also might consider an injector pointed upstream into the airflow. Warning though it could get a touch dangerous and you wouldn't want it to spray on the maf. I'll check out the site and see if I can find any enhancements to make.

 

I think since the system must ramp up to pressure and there is no head pressure
(no solinoid) that you may choose to activate it earlier and up the aggression of the pump engagement. Just an idea and my previous mention of the maf sensor might be invalid. It might be okay for methanol to get on the sensor but the engine may run richer.

 

The MAF stays maxed out at anything over 10 psi boost.

 

Okay, this is getting d@mn ridiculous. . . I put everything back together over the week and drove it again tonight. It runs perfect at 11 psi and no Methyl. At 19 psi with Meth, it stuttered the first time I hit the gas (same problem from a few weeks back that new plugs fixed), then it backfire/exploded the 2nd time I hit the gas. My radiator and its top support can't take much more of this. The first time, it only cracked the top support. This time, it broke it in two and dented the radiator!

Mike

 

Did you happen to be logging AFR at the time? I think you're lean, or you have weak intake valvesprings that float under the higher boost.

 

sale me your alky kit

 

I added 10% fuel to the PE tables after the first backfire. The A/F this time was 12.5 at the leanest.

I did experience suspected valve float on the dyno. At 5800, the power curve gets jagged and falls off. Why would it only backfire sometimes, though, if it were valve float? Seems to me like it would do it everytime if that were the case.

Mike