I went camping near King's Island in Ohio last weekend and had no problems going there nor while I was there, but about 100 miles into my 250ish mile trip home the X started running rough. Towed down there using the 87 performance tune and when I got there i filled up with 93 octance (35gallons) and loaded in the 91 tow tune. When I pulled over, I called Mike at 5star, he advised me to load in the stock tune and said it sounded like a COP going bad, and he told me to keep RPMs up and overdrive off. I followed his recommendations, talked with my mechanic he agreed. Now, remember I am 150ish miles from home towing 6000# trailer and 6 people on board.

Well, the X got us home and off to the mechanic it went. So to make a long story short, new plugs and coils helped but did not fix the problem, new lower plastic intake helped(had a hair line crack in original one), but did not solve the problem. Latest is #5 cylinder has no compression!! Not sure what the true problem is just yet, hoping just a valve spring rather than a bad valve. The X was running absolutely great with no problems until this incident, and has been maintained.

Now, I am really bothered by this on one hand, on the other hand I think this is one hell of a truck and I am lucky, not only did it get us home but while the mechanic was test driving it after some of his repairs, IT BLEW A BRAKE LINE!!!!! What better luck for it to blow under those cirmcumstances vs while I was towing home, or worse yet I am towing again in 3 days ( hopefully with a repaired X).

I will update the thread as I learn more.

 

Wow, glad you made it home.

 

Thanks, we are glad too.

I have to admit, I have been wondering if the 91 tow tune contributed or caused this problem. I am not bashing or accusing 5 star or Mike at all, I have had great results with the 87 economy and performance tunes, but this was the first time I ran the 91 tow tune. Mike has been very helpful thru this and I greatly appreciate his help.

Driving home under those conditions and wondering if we will get home weighs very heavily on a person's mind. Again, the truck is not done, so I am just letting my mind work overtime trying to figure the "how" and "why" this happened. For example, if it is a broken spring it seems like that is not all that uncommon, but if it is a bent or burnt valve, then "how" did that happen? "Why" did this happen?

 

i thought you werent supposed to tow with tune being used?

 

I never heard that, but that doesn't mean a lot, they make a "tow" tune which by the name alone tells me I can tow with it, others on here tow with tunes and 5star has a vid where the are towing with a tunes.

 

I doubt the tune caused it, whatever the actual problem turns out to be.

If the tune was that far off to cause any issues, you would have noticed it running like crap before anything broke or got burned enough to cause no compression.

 

Good point. Well, the latest is the spring is good and the valve is bad, how bad I don't know but the head has to come off so I will know more then. I am now debating on doing a complete head job.

 

my dad has a chevy diesel. ( i know sorry, i wouldnt own a isuzu diesel myself ) and he said his programmer for tunes says not to tow with them on because it runs hotter or somthing, i cant remember exactly. he thinks his injectors failed because of it somehow.. i figured its just a chevy...

 

We are not talking about diesels here. But there are tow tune and race tunes for diesels. With a diesel you have to keep the exhaust gas temp below 1200 degrees. None of the same principals apply here.

I tow with 93 octane tune from 5 star and tow a 14000 pound trailer. So be sure it is not the tune that is the problem while towing.

 

I have towed with my 5 Star 89 tow/performance for 130,000 miles; it's not the tune.

 

I have towed with the 87 performance tune with no problems too, and I don't believe it is the tune either, like I said I am just trying to figure out why this happened and I admit the first thing that came to mind was the tune. Mike from 5-star did say that if there is a problem with the motor the tune will make the problem stand out and that is why he suggested to re-load the stock tune to get home. After talking with a Chevy mechanic that works for Chevy's Nascar division, he also said the problem was most likely there before and it would have happened anyway, maybe not so soon or maybe it would have.

 

Can someone explain to me how I could "burn" or "bend" a valve while driving?? I don't understand. The truck was running fine, no leaks, wasn't burning anything, all fluids were good, I don't get it.

 

The only thing I can think of is if you had a vacuum leak from that cracked intake plenum, it MIGHT have burned a valve that way. Without taking the head off, you won't know what really happened.

Pics would go a long way to describe the issue once the mechanic gets it apart.

Did the mechanic pressurize the cylinder and verify that air is indeed leaking out past the valve? Which valve, exhaust or intake?

 

Yes he did and it is #5 exhaust. I will try to get pics.

 

Update:


Well I heard back from my mechanic and he got the heads back from the head shop, there were 2 bent valves. The heads have been redone and he will be installing them today. I was not able to get pics.


So, 2 bent valves....HOW DOES THIS HAPPEN?????