Thread: Road trip problems......very odd

Hey fella's.

Well I am safe now In NC.

Wednesday I left from Maine to make the 1000mile trip.

Let me just set the record, that my VE from Andreas Miko has been running flawlessly DD'd over 1hr every day with NO problems up until now.

However I do not think this problem is mechanical (impossible), I want to point out the irony, that NOT 40min into the largest road trip of my life with THIS car. And the car dies on me before I even left the state! First time it has EVER had an issue that forced my to pull over on the road!

So here is the deal:

Symptom reproduction requirement: Speed must be over 70mph. 5th Gear.

I will be driving, I averaged around 80mph the whole trip (32avg mpg), the car will feel %100. All of a sudden the car dies. No lights on the dashboard. Car still runs electronically inside. NOTHING cuts out, but for the motor. The first time it happened I put in the clutch and the car stalled. I pulled over on the freeway, popped the hood, and checked everything...looked fine. Got in, started her up, instantly started, idled perfect. So after this happened about once or twice every tank of gas (300miles). I began to relax and watch for a trigger or something? Well, it will cut out at any speed above 70, I realize I would just leave it in gear, and the car would drop to 70mph, at which point the car would regain power instantly and be back to normal.

So since I had over 15hrs on the road to go over and over what this could be. I realize it might be something with the tune perhaps. I have a Calum RT ecu, with a tune I have been slightly modifying on the street. I had set the 5th gear rev limiter to 6grand, and top speed to 120mph.

The car WILL drive over 70mph. This problem is very inconsistent. The consistency is in the fact it completely cuts out, and will instantly regain power after speed reaches 70mph.

This has NEVER happened to me before. I have had the car up to 120 with these current settings, and it acts fine.

Again, remember I was avg. 80mph so it is not a "above this speed car cuts out every time"


Any help would be great. The car has been driving fine, so I am not really worried. I just want to figure this out.

Long post, thanks or reading, I am long winded, if you didn't know that by now. Any clarification needed just ask.

Sincerely,
Dudeman

But, if it were a tuning issue shouldn't it be limited by RPM/throttle and not velocity? Maybe you've developed a wiring issue someplace, or the ECU has developed some sort of error related to speed (like speed limiter messing up)?

Have you tried going at high RPM and more throttle in 4th to simulate the engine conditions at higher velocities in 5th? That could help to figure out what's up.

That is a possibility, but the Calum ecu has 5th gear rev limiter and 5th gear speed limiter's nothing else.

I still have to try out 4th, but as I said, this would only happen ONCE every 5-6 hours of driving.

I did consider wiring, however it is way beyond me how that would ever cause a situation like this? As the motor will always gain power once speed is down to 70mph??

Drove the car all day today around town, without a problem.

Thanks for the suggestions, I am deffinently going to check all wiring for possible faults, or weak connections.

Dudeman

I hate this kind of thing. What are you using to switch your cams? If MSS, have you set any of the parameters other than RPM?

Sound like a vapor lock issue.

Summit window switch, set to 5300.....




Elaborate?

The problem is either a freak electrical problem that I fully intend to chase, or something mechanical that is beyond my experience to diagnose.

The motor was compression tested yesterday and yielded 180 on all 4 cylinders. Dyno was 173whp with n1cams...


Thanks guys.

Dudeman

This explains better than i can http://en.wikipedia.org/wiki/Vapour_lock.

You explained that it happened when the tank was full. there is less air in the tank when full. On the highway there is alot more fuel demand causing a vacume within the tank. Which causes the fuel pump to supply vapour to the engine.

Solution, inspect the fuel lines, look for any capped off lines.

My question related to Vapor lock...

When the motor stalls, does it stall instantly, as in a complete shut off? Or does it stumble to a shut off?

I would think that if it stumbled, it would be something fuel delivery related, but if it shut off instantly, it would be something different, like something electrical.

Instantly. No hesitation. When it comes back in, it pulls perfectly in 5th.

I have driven it everyday now since I have been down here with absolutely no problems. This is so weird ha. I even had it on the highway for 20min, was around 70mph. No problems.....

It is most deffinently electrical. However there is no possibility of a loose wire because it only happens over a certain speed, and always comes back on at 70mph.

It is as if a switch controlled spark. It was flipped off, then flipped on. to the T.

Dudeman

A overheated coil (coil on the way out) will do the samething.

With the vapour lock you would feel a loss of power or the car holding back.