Another TBI running rich

[opus]

Further more....

I just reset everything again. There is no way I am going to get the proper idle with the TPS set between .58-.59v, not even close. I cut the TPS voltage in half and got an idle I liked. Took it for a drive and it feels better. I know its not supposed to be set like that but I'm going to try it cold in the morning and see what happens.

 

[opus]

You said it's running rich and a number of people think vacuum leak, so by any chance is the valve lash too tight?

I highly doubt it. Its a 20k mile, fresh long block from a reputable builder. Plus its only running rich for 45 seconds. Definitely something electronic.

 

[PlayingWithTBI]

I cannot get the idle to go below 700-725 without my throttle plates sticking.

Check to make sure it's not the throttle cable sticking - when you lower the base idle too far the inner cable will extend past the sheath and jam.

 

[opus]

Throttle cable and cruise cable were disconnected....thinking the same thing.

 

[arrg]

Your log shows some spurious engine speed data about once per second, and it contains no data between 38-54 seconds. Just an observation; I have no idea if it's relevant.

 

[opus]

Heres a new log, as I was playing with TPS as well:

https://docs.google.com/spreadsheets/d/1XrVhV-QauLr0a0VwygWLf9Pg7Ke-6KWjGcoz_q7-MHo/edit?usp=sharing

 

[Leonidman63]

And you are still chasing a ghost, with a carb and such you could have solved your problem long ago.

 

[camaro354]

First off do you have the stock tbi intake manifold on the vehicle? These trucks have no air temp sensor so a heated intake and stock 195 tstat is a must, as that is what the computer is expecting to see. Data logs look okay, did the truck act up within the log you posted? I did see your BPWs spike when your CCP cycled. You may want to verify your CCP is functioning and that the canistor is not soaked with fuel, if so replace it. Fuel psi is another thing since your BPWs are pretty low and its rich, lower your fuel psi to 11. Lastly exhaust leaks before the oxygen sensor can cause a rich condition. Verify every joint and gasket is not burnt out. Assuming you still have stock exhaust manifolds in place. If you have headers on there, they will throw the o2 way out of whack due to different locations, flow efficiency and lack of sustained heat.

 

[opus]

First off do you have the stock tbi intake manifold on the vehicle? These trucks have no air temp sensor so a heated intake and stock 195 tstat is a must, as that is what the computer is expecting to see. Data logs look okay, did the truck act up within the log you posted? I did see your BPWs spike when your CCP cycled. You may want to verify your CCP is functioning and that the canistor is not soaked with fuel, if so replace it. Fuel psi is another thing since your BPWs are pretty low and its rich, lower your fuel psi to 11. Lastly exhaust leaks before the oxygen sensor can cause a rich condition. Verify every joint and gasket is not burnt out. Assuming you still have stock exhaust manifolds in place. If you have headers on there, they will throw the o2 way out of whack due to different locations, flow efficiency and lack of sustained heat.

OEM manifold, check.

195 tstat, check.

The truck was warm for the last log. I'll log it again tomorrow. It did do they same stumble today, in spite of what I did yesterday.

CCP? I'll check canister.

So I need to get a regulator to lower pressure.

No exhaust leaks, no headers.

Again, the o2 isnt going to do anything during this time. This issue happens generally within 15 secs of startup and is gone after a minute....everything is still in closed loop I believe.

 

[camaro354]

OEM manifold, check.

195 tstat, check.

The truck was warm for the last log. I'll log it again tomorrow. It did do they same stumble today, in spite of what I did yesterday.

CCP? I'll check canister.

So I need to get a regulator to lower pressure.

No exhaust leaks, no headers.

Again, the o2 isnt going to do anything during this time. This issue happens generally within 15 secs of startup and is gone after a minute....everything is still in closed loop I believe.

If you are able to log from cold startup past the bog that would be pretty useful.

As for lowering the pressure you would want to modify the stock regulator or get one of the aftermarket pieces (jet, summit, jegs all have one) for the stock regulator. These systems did not like the aeromotive types that you would splice into the fuel lines, as they caused the fuel psi to flutter pretty bad. Think they are too slow to react to the big pulses of the tbi injectors.

However I would hold off on lowering the psi, from earlier posts I thought it was something you had previously adjusted.

So to clarify everything is stock, besides a new shortblock?

With stock ecm as mentioned earlier timing needs to be somewhere between 0 & 4 degrees as too many things rely on the distributor reference to get away with advancing it more.

I will check back for the next log hopefully it will help. A few suggestions would be if you can monitor the fuel psi during startup and when it begins to load up, psi should remain fairly steady & consistent. Second if you connect a timing light to either the number 1 or the coil wire(can't remember which) and take air cleaner off and shine it at the fuel comming out of the injectors it can help to see their spray patterns and maybe you could spot an abnormality when it starts to bog.

As for open/closed loop... on a cold start it would be in open loop and earliest it could go into closed loop would be closer to a minute or more. There is a count down timer as well as the o2 sensor has to be able to swing before it should go into closed loop. If you are able to log open/closed loop and if the bog happens when it transitions that could help steer you in right diection too.