quote:

Originally posted by Rusty:
Very nice job! Hope your problems are over

I hope so too. (I will have to redo the cable ties before I leave port!)

Took a 3200 mile "test drive" to Denver and back.

The high end hp and torque are less, probably only do 85 now… but the low end comes in a bit sooner. Idle is more smooth. Overal drivability is good.

Used less than one qt oil. Apparently the lower end is good and tight. For a 454 running 3000 rpm I am very happy with this. No leaks or other problems.

My fuel mileage is up from 7.5 with the HO cam to 8 now, best it has ever been. For the size and weight of the coach I am pleased with this. Another overall plus. In all fairness, this engine change was coincident with the transmission change. The new torque convertor is claimed to be 4% better "lockup" at cruise, it does seem to be running slightly lower rpm than before at cruise. I suspect the trans is responsible for .2 to .3 mpg of the improvement.

Hopefully the valves will be stable with this cam. I will monitor compression in the future.

Meanwhile I hope we are in the "era of stability"

I now have about 18,000 miles on the engine.

Have Barth, will travel

Great to hear Steve. I am still at Larry's catching up on a few things before I head to the event area tomorrow.

Maybe after my event in October, I will head east for a need R&R, we will see.

Take care, Ed. I hope the people at those events appreciate what you do for them.

Looking forward to next time, let us know when you are out and around. Be well.

Have Barth, will travel!

Did you ever get the ECM tuned for the 454HO? A TBI system is speed-density and will not be able to compensate for the changes in volumetric efficiency of the new engine...

I am currently on the 3rd chip since the FI conversion. Since I just changed the setup again with this new cam I will tweak a bit more. I started this game with the old carb engine, got 6- 6.5 mpg. Switched to TBI system got 6.5-7. With the HO engine I was getting 7.5. Last run to Denver with the new cam I got 8!

The O2 levels and sensors are running in the normal mid ranges, I don't think the running mpg can get any better. 8 mpg in this coach is more than I expected.

I just got another, hopefully final chip to tweak some idle issues. Hot idle is a bit high even with minimal settings, otherwise running well.

I may be able to bump the timing a bit more bit I've been too busy doing stuff I should have done instead of the valve/cam job.

to be continued:

Steve - You might want to consider installing (or borrowing) a wideband O2 sensor with a gauge to just confirm what your AFR is. This would also be immensely helpful to whomever is doing your chip burning.

I think an AEM wideband is around $200 for a gauge with sensor. I tune my own EFI stuff, and I started "back in the day" by burning my own EPROMs for old TBI and TPI computers and now with the flash PCMs.

I'm just trying to help - you're playing with fire on a heavy RV without a wideband if you have a heavy foot like I do.

I have a 3 wire O2 sensor and I have the WinALDL app on an old PC so I can watch and log TPS MAP O2 TEMP etc through the ALDL connector. BLM numbers are pretty good now closed loop, but the low idle is open loop and just so much I can do with air flow.

I will have more data each time I run. A game in progress. Thanks for the input.

The narrowband O2 sensor is only going to be accurate when the ECM is trying to achieve [near] 14.7:1 AFR (with zero ethanol fuel). When you are laying on the gas try to get up to speed (or maintain up a hill) it will command a richer AFR, go into open loop, and then the narrowband O2 can only tell is if it's richer or leaner than 14.7:1, but not to what extent. The BLM numbers are determined based on running closed loop and trying to achieve 14.7:1.

Once the engine is in open loop the tune uses other tables to calculate the fuel required based on the load of the engine without O2 feedback. If you had a wideband to log the tuner can run the math on the numbers you send him and get that stuff much closer to correct. It will use the BLM numbers to skew some of these, but that's not close to reality and can make the situation worse.

Interesting… I didn't know it went open loop in accel mode.

As it turns out I have an AFR guage but have not installed that sensor yet. It will be interesting to watch at higher throttle settings. I need to get another exhaust bung for that sensor.

It appears that this early TBI system is neither fast nor sophisticated. The OEM chips are known to be pretty poor performance. Only good side these things have been around a while so they are fairly well known by the tuners. We shall see.

That probably uses the 1227747 or 1228747 ECM. Slow and old for sure. There are upgrade options to newer OEM ECMs that aren't too painful, if you want to keep the TBI. They are much easier to tune and log! They are practically open-source on the internet now, too.

You are obviously familiar with these systems. 1227747 it is!

Since I have the non electronic TH400 trans I am using that older ECM.

Next time I run it I will have the new chip in there. We'll see how it changes.