Hello all , I am working with a howell type system where I use the fuel only calibrations and need some help. I have 2 questions that I need help on plese.

1) I am have a howell 4.2liter prom/chip but it will not run right on cold start up. I have to hold accelerator to floor and then start it , it runs so rich it burns your nose and kicks like a muel till it warms up. What do I look for in prom to get the cold start right. After it warms up about a mile or two it runs like a top.

2) My second question is that I also have one of howells competitors proms also but it is set up for the same 4.2liter engine but is set up to run on the ignition module. Now, how or what do I look for on this prom to get it to look for the negative pick up off the distributor like the howell system works? Or what do I look for to turn off the ignition module stuff? I did a complarison of the two files and found a ton of differences but I am still a newbie and cant tell what the goods, bads and uglies are yet.

thank in advance for any info and would be greatly appreciated. Or even if someone could point me where to read up on these two things that is just as good.

 

More input?

What system are the howell 4.2 jeep setups running.

I'm assuming its a TBI setup? I have seen port conversions too?

What mask ID is it and what GM ecm does it use?

later
Jeremy

 

The timing and the fueling are, for the most part, seperate in the tbi ecms, if thats what your using. The one thing that will be different is that there will be error codes that are disabled if theres no module present. The timing tables and all that other stuff will likely be unused.

Ive found that the rich smell may in fact be the engine running lean. It will have a funny smell that burns your nose and eyes. This would also cause the bucking. If theres visible black smoke then you can rule that out. A check of the spark plugs right after startup would probably give you some useful info if in doubt about whether its lean or rich.

Also, what are you using as a trigger for the ecm? Just the dist.? The injector firings in the ecm are autonomous and theres no way to change the triggering thresholds unless theyve altered the hardware. One of the hardware gurus can probably tell you more on this.

 

Sorry for not putting enough info out there. I am using a 7747 ecm and the 4.3 liter tbi system and injectors. Or in short I have 2 tbi sytems one from howell and one that I made from using howells as a blue print.

I use the negative side of the distributor for my ecm spark pick up and have the howell spike/voltage piece in between the dist. and the ecm. (I would like to see a dagram of one of those too) It does burn rich on start up because the smoke is black and it puffs out wet black stuff onto the concrete but only on start up, after it warms up it runs great and starts great.

I did some comparing of the two bin files and found a bunch of differences in the cold start, cold start choke stuff but I am not knowledgable enough to tell what is good or bad yet. What I was looking at doing is taking these setting from one and putting them on the hard cold start chip. I have several chips to program so I can keep the good one for now in case things go bad.

One thing I would like to do is have someone look at the two and try to get some experience in what to look for and what someone else would do to correct it.

The mask ID is the one that came with the ecm so I'm not sure what info here is needed.

Thanks in advance for any more info and I'm sorry if I leave any more important info out.