I got my truck running (roughly), and am starting to program the bugs out. The stock PROM chip is causing the engine to flood during cranking. Here's the sequence of events...When I turn the key to the crank position, the injectors run "wide open", the motor rolls over and sputters and dies. I then pull off both injector pigtails/plugs, crank the engine over and it fires and runs for 5 seconds. After it dies and burns the fuel out, I hook up one of the pigtails, fire it up and have a helper plug in the 2nd injector pigtail after its running. At this point it seems to run very lean with both injectors firing a good pattern. I can fix the lean idle through programming, but how do I fix the flooding at crank? Is there a procedure for testing/adjusting the IAC?

 

Whats your coolant temp sensor reading

 

I can check it tomorrow. I haven't let the motor warm up enough to raise the reading on the temp guage, but I can get you a voltage and/or ohm reading off the sensor.

 

Im just wondering because if the sensor is reading like -130 or somthing it would add so much fuel it wouldent start.

 

I have read posts about guys knowing what temperature the sensor reads at, is there a table of voltages that correspond with temperatures available? Or do people just read the voltage and compare to the guage.

Another thought about the flooding, what role do the TPS and/or IAC play? I checked the voltage on the TPS and it is reading .7v. I have not done anything with the IAC yet.

 

Is the cam bigger than stock? Also check the MAP sensor.

 

Im sure their is a table for the coolant temp sensor. The coolant temp sensor is a thermosister which varies resistance based on temperature. So their might be a fixed resistance for a certain temp however am unsure. I check mine with a scan tool which most people dont have access to. Both tps and coolant temp are a 5volt referance. Tps seems okay at .7 if the throttle is closed however should climb to about 4.5 volts at wot. Dont take my word on that as each car has different specs. Have you checked for codes by chance im sure somthing is set if its running that rich. As for iac all i belive that does is set idle based on the number of turns or clicks the ecm wants it to do. So i dont think thats your problem

 

Yes it is - I bought the motor used and do not have the specs, but it is rather radical.

 

Update - I *think* its a two-part problem, but I need someone experienced to help me out. Currently, the motor is in a VERY rich condition both at crank and now at idle...

The first part I thought would have fixed everything but it didn't - it was giving me a code 15 low coolant sensor temp. All the plastic on the plug had broken apart over the years in the sensor and junked it up. I replaced the sensor, and temporarily put the wires on the pins until the new pigtail comes in. It's no longer throwing the code, but it's still running waaaaay rich at idle...

The second part is that the cam is very aggressive and I *think* that it's just confusing the heck out of the computer with vaccum. I've tried leaning out the PW and leaning out all the open-loop tables in the computer, but it seems like the more I take fuel out the more the computer self-compensates and keeps it rich. I checked the MAP sensor function by unplugging the vacuum line and it quickly stalled out. It's almost as if I could amplify the signal from the MAP that it would lean out, but then again it seems like the computer keeps countering my programming efforts.

The motor is starving for air. I unplugged all the vacuum hoses except for the MAP sensor and it actually idled by itself, but was still a good bit rich.

Here is my troubleshooting steps today...

1) Replaced the coolant sensor and tested the wiring - no more codes.
2) Tested MAP function (Didn't test voltage, just pulled the hose)
3) Leaned out the PW settings and leaned out the open loop settings in the computer. BPW constant is currently set at 130.
4) Just for kicks, I plugged in the stock 4.3 PROM and it actually idled decent, but was still a bit rich.
5) I adjusted and tried multiple ignition timing scenerios and none made much of a difference. I just don't think it's a timing problem.

I'm desperate for opinions. I made a ALDL cable and will be able to hook it up this week with my laptop, but I need to get the thing to idle first!

 

How about VE values?... https://www.thirdgen.org/forums/tbi/...-constant.html

Mine were waaay off from a stock 350 table...

 

What does it do when you increase the throttle alittle bit? Is this a new setup and trying to get it to run?

 

Yes this is a new setup from scratch. I think I'll put my info into my sig later today to give you an idea of what I have. Essentially it is a 1972 Camaro 350 engine and 350 tranny with a 1992 Caprice TBI setup and a pretty aggressive cam. I bought the motor used and the fellow didn't have the specs on the cam, but as soon as it fired my dad and I just looked at each other and said "oh boy", knowing it would be a little more than what we had bargained for with a daily driven vehicle.

When the throttle is anywhere from 400-1400 RPM's it stumbles really rich. After that it revs pretty decently, it sounds fairly close to where it needs to be.

After looking at my table values, the ones that were most "off" from a stock 350 were my main VE values which were about 10 high all across the board. One person here was kind enough to offer me their cammed-up VE table which I think will help alot. Can anyone tell me what 10 points mean on a VE value? Like how much does those 10 points effect AFR or what do they mean in real-world or old-school situations?

 

The problem is fixed - if anyone else runs into a flooding condition @ startup, here is what caused mine and my solution:

1 - I had a bad Coolant Temp Sensor pigtail and wire that needed replaced. The motor thought is was
2 - My VE tables were all wrong.
3 - My AFR settings were all wrong in the ECM. For starters, I had mistakenly entered every value as a stand-alone without realizing that multiple values add together in open loop to come up with an "overall" .