Need some help with my 4.3 CPI

[ain'tstuckjustresting]

Also make sure you have a full charge on the battery.....Low voltage can make it do strange things....

13.8v @ the ECU check using the all 3 ecu ground pins also.

 

[zukkev]

Seems to me (from memory) that a couple plugs on the various sensors with this system can inadvertantly be plugged into the wrong sensors...could that be it (check the wiring closely...)???

 

[ain'tstuckjustresting]

The plugs are all different and the pigtails are really short. I haven't found any plugs that would interchange.

 

[Binder]

I did the procedure as stated, jumping the aldl, key on, unplug IAC, key off, remove jumper, start engine.

Which should have closed the IAC but you say it didn't. This leads me to think something is wrong with the system as it relates to the IAC......

So this is what I tried: I created a metered vacuum leak (Booster line and clamp) and closed it down to achive the lowest smooth idle w/o surging (about 900rpms). I put my finger over the IAC port and can't feel any vaccum so the pintle must have closed.:

At this point you should be able to close that vacuum leak and the IAC will open correct?

I open the throttle a bit and can feel the IAC start to pull vacuum on my finger. It must be reacting to the TPS command and allowing more air in to increase rpm. If I continue to block the IAC port with my finger and open the throttle more it will pull even harder through the IAC port. In a correctly operating system this is what you would expect right?

Yes this is what I would expect but that doesn't mean it's working exactly like it should.......I would hate to send you on a wildgoose chase here and it's hard to say over the net exactly what is going on. It SEEMS as though the IAC isn't working quite right by what you've said. Why that is is hard to say...
Is this a stock computer?

 

[Hip]

I bought the harness and eprom from Howell EFI. I got a copy of the pinouts and haven't found any discrepancies yet. Not serious supply voltage issues like you had either. My TPS is dead nutz .6v at throttle closed as per spec, so I don't see why that would need to be adjusted to .54 as listed in the link from Binder.

They guy at Howell was a douche when I called him, pretty much no help. He said they test all the harnesses and chips before they leave so there must be a problem with the engine or ecu.

Company i bought mine from said the same thing.

I'm pretty sure all the TBI info in the link is for the older ecu with the black plugs mine has the red and blue plugs. I'm not sure that info will work on a Vortec.
i have the correct pin out and they are different.

I just had the plenum off last night to double check everything. It was oily in there from the very rich exh being pumped in by the egr but there was no fuel pooling around the lines or regulator. I cycled the pump a few times to make sure there were no leaks.

I made a block of plate for the egr just to eliminate a stuck pintle. I'll remove it once I get it running decent.

I'm pretty much at a loss here.

Hip, did you have to use the DRAC or VSS? When I bought the harness they said none of that was needed for the engine to run, but when I talked to the douche at howell Friday he said he thought the DRAC needed to be hooked up.

no my chip takes care of all that tranny shift stuff. the ecu will run the motor just fine.

i had to get a magnafying glass to actually read the pin numbers on the connector to find my wiring issue as it appeared to be correct. i didnt find it till the third time i checked it this time with the glass. the way the wires lay in the harness they were jumping over each other and looked correct. when i removed some insulation and spread them out some and did a pin by pin wire check and verify the other end simultaniously with a meter. then i checked it again, then i had someoene else check it. then i swapped the wires to their correct place and she purrs like a kitten.

i spent a fawkin month.

you will need to verify voltage while running at each component the scan tool does that for you

bring it over saturday, i also have a full set of compoonents to swap out back and forth.

if i need it i have a perfectly stock runner available to check original stuff.

i had incorrect voltage to a few things as the pin was supposed to have 5V output and actually had 12V input:looser: MAP was wide open telling the ECU to give it wide open throttle so the injectors were on full blast. i went thru 5 gallons of gas in an hours running time. sound familiar? nothing was leaking it was going through the cylinders....

 

[ain'tstuckjustresting]

Well the way I'm reading things it should run decent with everything unplugged but the MAP, TPS, ECT, and IAC. During open loop those are the only 3 sensors the ecu needs. Well I checked the input signals on all 3 at the 32pin connectors and they are in the standard range for warm idle. It still runs pig fat though. Everything points to a internal fuel leak but there are 0 leaks, all new parts and it holds 60psi for a long time key off.

I really want to download winaldl or datamaster but I don't have a serial port on my laptop so I need to order an aldl cable for usb.

I'd love to bring it up to ya but finding the time to get to Everett is an issue right now. Thanks for the offer!:awesomework:

I have all the factory diagrams for a 94' which according to howell is what I must have. I have a 16196395 ECU which they said was only used in 94' for the 4.3. It was used other years for diff engines.

My harness is pretty easy to trace, the wires come straight out and the insulation is back about 8".

I'm going to take it over to the shop tomorrow night and make sure I haven't done something ignorant like put the dizzy in a tooth off or f-up the firing order (even though I've already checked 3 times)

 

[zukkev]

Well the way I'm reading things it should run decent with everything unplugged but the MAP, TPS, ECT, and IAC. During open loop those are the only 3 sensors the ecu needs. Well I checked the input signals on all 3 at the 32pin connectors and they are in the standard range for warm idle. It still runs pig fat though. Everything points to a internal fuel leak but there are 0 leaks, all new parts and it holds 60psi for a long time key off.

Sorry but that's 4!!! :fawkdancesmiley: And you also need O2....
What exactly is the MAP signal voltage at idle???... and IAC counts for that matter...What's the O2 Voltage reading too??? (all closed loop numbers)...

 

[zukkev]

For that matter, what's the V-pwr voltage to these sensors???

 

[ain'tstuckjustresting]

But sir IAC is not a "sensor":kissmyass:


This thing runs like shite in open loop so I doubt the O2 sensor is causing this
I have no way of reading IAC counts w/o a scanner, Input voltages are right on 5v for the TPS,and MAP Didn't read the ECT but when at op. temp it sends 1.7v to the ect signal pin the sensor reads 231ohms at 190deg which seems pretty close.

Didn't check o2 voltage but ran it unplugged and saw no change if performance.

Forgot to write the MAP signal down while running poorly but with the metered vacuum leak and decent running it reads 1.2v @ the ECU.

I've got **** scribbled all over this damn pcm symptom chart.

 

[zukkev]

What's the O2 signal reading...Even in open loop?

 

[ain'tstuckjustresting]

Don't know, I'll have to check tomorrow night.

 

[Binder]

What's the O2 signal reading...Even in open loop?

I'm gona guess zero if it's unplugged.:flipoff:

Aint stuck.....What modification have been done to the engine?

 

[ain'tstuckjustresting]

Other than all the vacuum canister **** removed, nothing that I know of. I bought the engine off the board and is was supposed to be freshend up with stock specs. It was 90% assembled when I got it so all I did was check the bearing tolerances and retorque everything. I don't have a build sheet.

The Howell chip is supposed to run it as is. The only thing I didn't plug in was the DRAC and VSS.

I guess it does have a Summit coil, Summit cap/rotor, Taylor wires, Stock AC Delco plugs, Astro tube manifolds, booty fab air cleaner, etc.............

 

[zukkev]

I'm gona guess zero if it's unplugged.:flipoff:

Aint stuck.....What modification have been done to the engine?

Could be .45V too! :fawkdancesmiley:

 

[Hip]

I really want to download winaldl or datamaster but I don't have a serial port on my laptop so I need to order an aldl cable for usb.

I'd love to bring it up to ya but finding the time to get to Everett is an issue right now. Thanks for the offer!:awesomework:

well i could let you borrow it i guess. if ya can find a way to swing by or have someone i know swing by?

 

[ain'tstuckjustresting]

So I got my Datamaster loaded up and recieved my usb/Aldl cable so it's time to tinker.

Not sure what the hell I'm even looking for but I was hoping to find a 0 value or something way the hell out of range but no such luck.

I recorded for 30min running on the trailer. It won't idle so it's kinda tough to get good baseline readings.

Only took 3min from cold start to go into closed loop. Eng temp was only 96deg.

Added a couple of snapshots. Not sure if it helps.

 

[ain'tstuckjustresting]

I can post the whole session but you need Datamaster open it. (it's free):awesomework:

 

[Binder]

I can post the whole session but you need Datamaster open it. (it's free):awesomework:

Post a whole session...In Notepad the titles don't line up with the correct column so it's kinda hard to read your snap shots. Can you save them in Excell?
At first glance the only thing I see strange is the timing keeps going retarded at idle. I don't know why it would do that unless it's getting spark knock....

 

[zukkev]

How do you open these files? (I can't seem to be able to...:booo

 

[Binder]

How do you open these files? (I can't seem to be able to...:booo

The ones he posted? They're .txt files which should open with note pad.