Ok, here's what Ive got. 88 chevy truck 350 TBI. I just swaped in the 330 HO motor. Holley 670 TB. Headers, no cat, flowmaster exhaust. Custom prom. all new sensors. The truck runs well once it heats up, but when it is cold it runs so rich that it almost dies. I can hold my finger over one of the injectors and it makes a real big difference(smoothes out) Once it gets hot enough for the O2 sensor and MAP sensor takes over it runs pretty good. Does this mean that my custom prom is not quite custom enough?
Thanks
jimmy

 

i have that engine and had the same problem with mine, would make a nice cloud of smoke on start up and intill it would go in to close loop, then it would run somewhat fine, you might want to check the fp and ajust it a little. check to see if all the sensors are right and the tps is correctly calibrated. well to say what solved my problem was well your not going to want to hear it but i had to go to carb, i was not giong to burn my own chip because i was not sure if i really could get it good enough to were i wanted it and was debating wether or not to put more money in to the tbi system.. i got every thing i need for going back to tbi when i want to and its like a 30 min job so if somthing pops up i might have to see if it fixed all my problems

 

Borrow a laptop, build the $4.00 interface for winaldl and look at the BLMs. If the BLMs are around 126/128 but the problem is still that it's running rich only when cold...then there is still an eprom issue. Considering both the fuel and timing is completely dependent on the eprom I would say yes...eprom needs recalibration. I would only pay for it to be fixed if the guy tuned 3 ways: 1st way is to use a dyno but that's expensive, 2nd way is to use winaldl and look at the BLM when the car is warmed up, if you're running really rich in open loop then my bet is that your BLMs are probably down below 120, maybe even pegged up against the 108 limit, 3rd way is to have the guy lock the eprom's BLMs values min and max being set to 128 (stock it's something like 108 min and 140 or 138 max), by locking the BLMs he can then look at the o2 voltage vs Map pressure and build a good VE table that way.
If in closed loop the BLMs are near 128 and the truck is still running rich in open loop then there is an AFR vs coolant temp table that he can adjust.
Tell him exactly what I said and if he doesn't understand any of it do your own eproms. I can walk anybody through the process of burning a good eprom...it only requires that you take the first step and get the tools.

 

John,
I took the truck to a local mechanic that I trust, he put a scan tool on it and he said the BLM's are at 108, what do I need to do?
How difficult would it be for me to burn my own chip?
Thanks
Jimmy

 

It itn's difficult to burn an eprom (aka "chip") for your vehicle.
I can walk you through the process and steps needed but it'll take some interest on your part.
BLMs at 108 tells us that your ecm is seeing WAY too much gas and it's running super rich. The BLM of 108 is when the ecm is removing fuel from it's built in tables. You need to turn down the fuel pressure but better yet (so you don't run lean higher in the rpm band) burn your own eprom. You won't be sorry and it's a gift that sticks with you for life. $230 and you could have EVERYTHING you need to burn a custom eprom for you truck.
To make things easy e-mail me and we can talk about winaldl.

 

This thead describes my camper exactly also. I have been cutting back on the coolant temp / afr to help out the cold rich problem but it does run much better when goes to closed loop. it has 108s at the lower RPMs close to 128s as the RPM get higher (2400ish). It has very bad flat spot and cough when you jump on it so I have started raising the pump shot. It seems there is not enough of a shot volume wise even though I have been raising the "USEC" .
330 hp Delux
670 Holley
9000 pound vehicle
65MPH= 3200 RPM

 

With BLMs at 108 you're probably making the engine so rich that spark is having trouble jumping the gap. You said you adjusted the pump shot values so you must be burning your own eproms. Get the BLMs to 128 through the whole rpm band and MAP range. Only after you do that will you be able to notice results with changing the pump shot values.

 

Thanx, I'll have to head that way. I was trying to start out fixing it while still in open loop and working forward. Prob. thinking all wrong.

 

be careful!!! BLM of 108 is the LOWEST BLM allowable by most TBI ECU's. What this means is that the ACTUAL BLM could be 80, or anything less than 108, but the ECU will not go below 108. you need to burn a new chip with BPW multiplied by 108/yyy where yyy is the BLM on the cip you have now. Then, run the scan tool again and iterate the process one more time. When you put the first burn PROM in, the BLM's should be higher than 108 and the second iteration will get you even better.

 

OK, Adjusting the VE tables...
The 7747 has two Ve tables.
1) Which (or both?) is used during open loop?
2) What is the criteria for choosing one or the other to adjust?

 

The first table is what you should really play with the most considering it's got the MAP settings so it's more specific compared to just the engine speed alone.
In both open and closed loop both tables are added together, this is a percent so they should never add up to more than 100 or it'll be defaulted to 100. Just add what is in the second table to the whole row in the 1st table, that's how you get the final fuel values (not counting other situations that would remove and add fuel depending on special instances, WOT, EGR, tcc, Etc.)
The funny thing is that all along I've been just setting my second table to all 7's and then just adjusting the 1st table. I think this is the wrong way to do it after talking to Pablo last nite. The 2nd table goes up to 6400 and the 1st table only goes up to 3200. So you need to adjust the values after 3200 in the 2nd table. I'm going to change the table to all 33's and then after 3200 I'll start decreasing the values slowely. This way I don't run super rich at higher rpms likve I've been doing.
It was knew news to me but it makes perfect scence, I'll try and verify it when I finish building the test bench.

 

So that leaves me a bit confused of the purpose of having two seperate VE tables.

 

The only reason I can think of is that you can edit the second table if you notice that the BLMS at a certain rpm and ALL map values are extreme high or low. So you don't have to actually edit all the values in the 1st table.
Other than that it's worthless except that it goes to 6400 rpm!!! This is why it's critical to adjust after 3200rpm on the 2nd table.
It would have been nice if there was just one huge table from 400 to 6400rpm but it isn't, so you just have to take the row at 3200 on the 1st table and pretend that never changes after 3200 so you must adjust the second table.

 

Hmmm... My four an a half ton tank cruises 65MPH at 3200 RPM I'll have to rely heavily on this list.

One other item, EGR? I don't have the provisions for this on my 330hp HO. I have seen posts here that turning this off is inversed. Is this true of the value in Tuner Cat? I see it uses temps. or is this the hex value or how does that work? TC or Win ALDL (I forget which right now) shows values for EGR on and off for TPS and VSS, DO all these need to be changed to keep EGR disabled?

 

Yeah, the temps are inversed in TunerCat and the general rule. Turn the temps to -40.7 or whatever the extreme. You don't need to mess with any of the other settings and can just leave them alone. What kind of gears do you have to be running 3200rpm!!! Do you not have overdrive or are you running some >4.55s and small tires?

 

I haven't tried to figgure out the gears ( just need to measure a tire some day) but I did not even know the RPM until I tried to add fuel injection and all the GREAT people on this board started helping me. I Have it all working with the ALDL tool to see what is going on. But yes, smaller tires and TH400 in a heavy camper. I hope no one holds this against me.