My Viper caught fire on Dyno at 5000rpm !

[Schulmann]

Okay guys. I know that you all opened this post to see the pictures showing the big flames coming out of rear of my Viper. Yes I had 30 feet long yellow flames coming out of the rear of my Viper. Once the engine was stopped the flames turned upward toward the ceiling and continued to burn for 15 seconds. I can tell you that when your Viper burns the first thing that you try to do is to save the Dyno man caught inside your car. Then you look for the only fire extinguisher of the workshop that hasn’t been used for 35 years since the shop is opened. And when you can’t stop those flames you are having all those dark ideas: “Men I should have bought 5 Toyota echo for the price of my Viper” or “I would like to be with my wife in a hot tube miles from here and never bought this car”. And then you realize that there are 1 million dollar worth rare cars around yours that they could burn too. Then you thing about what your insurance covers exactly.

And finally the stupid flames stopped and everybody was wondering what went wrong. My dark ideas also left my head. Instead of kicking me out with my Viper the guys all put together their heads to figure out what went wrong. We decided to unmount all the spark plugs. Plug No10 was black and the cylinder smelt like my gas tank. In fact the plug’s little top bolt was not fixed tight and this is what caused the misfire in my engine. In addition I am having ignition problems around 5500rpm, this is why my car was on the Dyno.

Fortunately nobody got hurt!
My car runs “fine” but still has this ignition trouble.
There is some paint missing on the rear bumper but that’s just a little paint job.

My Viper is happy to be in one piece and so I am.

The only trouble left is my wife, she is really mad … and scare to go for a ride.

 

[Larry Macedo]

What modifications do you currently have?

 

[ChicagoGTS]

Some kind words for when you get your car dialed in:

A.) your wife will always be mad because I garauntee this isn't your last mod.

and

B.) After you take her for a ride to hell and back she will always be scared to get in again.

 

[JGK95]

Chicago,

Again, Great knowledge dispensed! LOL!! My problem will be when she enjoys the Speed and Kicks me out of the car and goes for a ride! =O

 

[DodgeViper01]

Thank God no one was hurt.

 

[Jack B]

andkovacs:

One plug with a loose plug cap didn't cause what you described. The car had to be dumping raw fuel into the exhaust prior to the misfire. If raw fuel hits the O2 sensor, the sensor will show drastic lean. The PCM would interpret this as trouble and further enrich that bank. I would say the likelihood is more like an injector not turning off, but, why is the hard part.

Are you using any device to modify the a/f curve or is this a stock PCM. Can you post your a/f curves prior t this event and please don't tell us you didn't take a/f readings. If you did take a/f readings, where was the O2 sensor located and was it located in the bank that caught fire.

What type of miss are you experiencing?

 

[Schulmann]

I have installed a SC and having troubles around 5500 rpm. Some sort of electrical trouble. When the car really heats up the AFR gets rich 10.5 from 13. And this happens without changing a single parameters. I have re-grounded a couple of wires and the situation improved dramatically but there is still miss fire around 5000-5500 rpm.

So the raw fuel came from miss fire and faulty sparc plug wire. Injectors seem to run perfectly.

 

[99 R/T 10]

What kind of S/C are you running?

 

[Go Fast For Life]

Need video

 

[Schulmann]

Need video ?! There won't be any replay
No stuntman available for this type of movie.
When your car burns you drop your camera and you run for en extinguisher faster than Ben Johnson.

Finally my wife will come for a ride.
We are leaving for an outing this week-end.
I bought an extinguisher to reassure her.

But what really bothers her is the missing paint on my bumper.
You know she is a fashion designer and “can’t” show up in a public events with a half burned Viper . I put some black rally tape on the rear so it is no longer so visible.

 

[J DAWG]

What kind of S/C are you running?

ditto

 

[Finally got it !]

What kind of S/C are you running?

From a previous post he is running a Roe S/C. Unless something has changed.

 

[Qualitywires.com]

watch out for wash down!

 

[Cop Magnet]

andkovacs:
If raw fuel hits the O2 sensor, the sensor will show drastic lean.

Don't you mean drastic rich??

 

[Venom 1000TT]

Welcome to the Club! My insurance just paid over $10K for my back end repair & it looks like crap! Crooked stripes etc. Always & I can't stress it enough, always carry a fire extinguisher in the car. You're lucky it happened on the dyno versus me out in the middle of no place. You weren't using any fuel management system were you? Well like you said fortunately no one got hurt! But it sure is a scary thing to happen!

 

[Miles B]

Cop Magnet,

No, I'd say it would think very lean. The sensor measures concentration of oxygen, and as it is covered in wet fuel, it can't do its thing.

 

[Jack B]

cop magnet:

Miles is right, raw fuel on the O2 shows lean.

 

[Schulmann]

I had the impression that with full throttle the front oxygen sensor's ouput is ignored by the PCM.

 

[Sean Roe]

I had the impression that with full throttle the front oxygen sensor's ouput is ignored by the PCM.

That is correct.

If there was a spark plug wire was disconnected while the car was being worked on at the dyno, or if the wire lost connection as the engine went into boost (path of least resistance), the raw fuel in the exhaust will light and burn. When doing driving instruction at the Justin Bell school back in 2000, one of the school cars (1998 GTS) caught the rear bumper on fire during decelleration (I was 2 cars back). The only thing about it before hand was that the check engine light was on and all instructors complained about the fuel smell.

While it's certainly possible that a cylinder not firing was allowing raw fuel to be dumped into the exhaust (also given that the dyno shop found what they determined to be a problem), we're also looking forward to getting the PCM, MAP sensor and VEC2 back to verify those systems are working properly.

Glad you're ok and that your wife will ride in the car again.

Regards,
Sean

 

[Schulmann]

I just shipped the computers and the MAP sensor ...
We had an outing with the local Viper club, 500mi over 2 days. The ignition is not perfect but the car runs safe ...
My wife was also re-insured that my Viper is safe.

The raw fuel was purely related to a "disconnected" sparc plug wire on Cylinder #10.

After 32 heavy runs on a Dyno it is "normal" that some bolts can get loosen ...

 

[Jack B]

Sean:

I believe there is a scenario where the O2 will affect open loop. It happened on my car. If the O2 senses a dramatic change (lean) in a/f over a short period. It will enrich that bank whether in closed or open loop. During one dyno pull the car pulled a service engine code and subsequently sprewed fuel out the tail pipe on the left bank. The code indicated the bank went rich to offset a noted lean condition in that bank. I believe that lean condition was initiated by the notch and raw fuel hitting the O2 sensor. What are your thoughts on that scenerio.

 

[Sean Roe]

Hi Jack,
A rich or lean code is set by the long term fuel trim adaptives reaching the end of their adjustment. Depending on what type of scan tool is used to read them, they generally have a value range of -32.8% to +32.8%. That's just a reference value though, it really doesn't have that much of a range. If you got such a code, you need to:
- Check the adaptives and see where they're at.
- Listen to all the injectors and make sure they're working.
- Make sure all the spark plug wires are connected properly.
- If there's no trouble found with the mechanical items, go to the Fuel Options page. Verify you're using an injector offset of about 61% for the green top injectors. Begin changing the individual trim settings on the left and right bank until you achieve a zero adaptive adjustment. The engine will run best here.

In regard to the question you had on oxygen sensor monitoring during open loop, here is the text copied from the shop manual:

MODES OF OPERATION

As input signals to the PCM change, the PCM adjusts its response to output devices. For example, the PCM must calculate a different injector pulse width and ignition timing for idle than it does for Wide Open Throttle (WOT). There are several different modes of operation that determine how the PCM responds to the various input signals.

There are two different areas of operation, OPEN LOOP and CLOSED LOOP.

During OPEN LOOP modes the PCM receives input signals and responds according to preset PCM programming. Inputs from the upstream and downstream heated oxygen sensors are not monitored during OPEN LOOP modes, except for heated oxygen sensor diagnostics (they are checked for shorted conditions at all times).

During CLOSED LOOP modes the PCM monitors the inputs from the upstream and downstream heated oxygen sensors. The upstream heated oxygen sensor input tells the PCM if the calculated injector pulse width resulted in the ideal air-fuel ratio of 14.7 to one. By monitoring the exhaust oxygen content through the upstream heated oxygen sensor, the PCM can fine tune injector pulse width. Fine tuning injector pulse width allows the PCM to achieve optimum fuel economy combined with low emissions.

For the PCM to enter CLOSED LOOP operation, the following must occur:

(1) Engine coolant temperature must be over 350F.
· If the coolant is over 350F the PCM will wait 44 seconds.
· If the coolant is over 50'F the PCM will wait 38 seconds.
· If the coolant is over 167*F the PCM will wait 11 seconds.

(2) For other temperatures the PCM will interpolate the correct waiting time.

(3) 02 sensor must read either greater than .745 volts or less than .1 volt.

(4) The multi-port fuel injection systems has the following modes of operation:
• Ignition switch ON (Zero RPM)
• Engine start-up
• Engine warm-up
• Cruise
• Idle
• Acceleration
• Deceleration
• Wide Open Throttle
• Ignition switch OFF

(5) The engine start-up (crank), engine warm-up, deceleration with fuel shutoff and wide open throttle modes are OPEN LOOP modes. Under most operating conditions, the acceleration, deceleration (with A/C on), idle and cruise modes, with the engine at operating temperature are CLOSED LOOP modes.

Regards,
Sean

 

[thebigsnake]

Andras, I was sorry when I saw your name next to this post.
However its entertaining as always.
Sean's electronic programming sounds mind boggling.
Take care buddy.

 

[99 R/T 10]

I just shipped the computers and the MAP sensor ...
We had an outing with the local Viper club, 500mi over 2 days. The ignition is not perfect but the car runs safe ...
My wife was also re-insured that my Viper is safe.

The raw fuel was purely related to a "disconnected" sparc plug wire on Cylinder #10.

After 32 heavy runs on a Dyno it is "normal" that some bolts can get loosen ...

What bolts?

 

[Schulmann]

Really any bolts ...
After a race you should always have a full check up on your engine.
In my case it was the small "bolt" on the on the top of sparc plug that get loosen.