MPFI Questions

[Heckelbone]

Re: MPFI in the works

Wow! I am so happy to see someone with the same setup I have. I wish I would have taken the time to polish my rpt intake manifold.

I use the ostrich 2 from moates with the bluetooth adapter. It works great, only fried once, my buddies are shocked I can reprogram wirelessly in a 1974 Scout.

I still have issues though. Seems now I only get cross counts on the o2 sensor when I'm at idle. If I step on the throttle the o2 sensor moves to 0vdc. I don't get smoke, but I keep having the clean my plugs, they get fouled every 400 miles.
I will attach a log of this.

Any thoughts?

Thanks,
rob.

 

[ldo_marlin]

Re: MPFI in the works

I can't read your .adl log file . Looks to be a some type of binary file. What software are you using to log? I am using tunerprort.

Not sure what the o2 problem is since I can't read the log file but here are some things to look at

-is the ECM in close loop at idle and stays in close loop when you hit the gas pedal (tps)? Check the bin and see what it's commanding the ECM to do?
- check the initial voltage (before starting) and after starting at the ECM pins. You can find the 1227730 ECM wiring data on the web. The o2 sensor should be an input signal to the ECM . May be wrong wiring?

 

[Heckelbone]

Re: MPFI in the works

I also use tunerpro rt. I will include the .xdf and .bin if those might help. Btw, this is a 345 with mpfi.... The afi kit.

That .adl log file shows it switching between open and closed loop. I have the o2 sensor (non heated) just below my driver's side header in the mounting flange.

I did have a voltage issue, was dropping to 8vdc. I put a new 3 wire alternator in and now it is always between 12-14vdc.

 

[ldo_marlin]

Re: MPFI in the works

I was able to look at the .adl file. Here are a few things I see

- it was in open loop the whole time except for 1 time point right before the engine was shut off (probably a glitch in the sw and the ECM never was in close loop) .
- coolant temp highest was 65c (149f) right before shutoff
- you had a voltage problem (~11v while running). It was fine (14.3v) about 2/3 through a few time points and then it went back low. Was this one adl run or multiple runs? If it was one, you still have a voltage problem
- tps value never changed


it's possible that the o2 sensor was never hot enough for the ECM to into close loop. On some application, depending where the o2 sensor is installed in the header pipe, it will drop out of close loop at idle. And will go into close loop when rpm increases (o2 heated enough)

can you create a separate thread on your issue? Or May be the admin can move the messages to a new thread.

 

[Heckelbone]

Re: MPFI in the works

There are two sessions in that file. The first is just a few minutes at idle, the second is much longer.

 

[ihpartsjeff]

Re: MPFI in the works

Posts moved to a new thread.

 

[Heckelbone]

So, I logged some data on my way home, and I almost made it there. I suspect my plugs are fouled again it is so Rich.
While I wait for a tow, here is the data I collected.

R.

345 mpfi, tunerpro rt.

 

[ldo_marlin]

I looked over your log and I am not sure I understand your initial complaint

"seems now I only get cross counts on the o2 sensor when I'm at idle. If I step on the throttle the o2 sensor moves to 0vdc. I don't get smoke, but I keep having the clean my plugs,"

from the log, your o2 sensor and cross counts are ok at idle and other rpms.

What I see is a problem right before your egine rpm goes to 0 , you're coasting aroung 11mph , your voltage starts dropping and it's unstable. After the engine quits, the log shows voltage bouncing around 12-0v. Something is shorting out. Any burning smell? Smoke?


Other problems I see while engine is running:
- your blm is very very lean in closed loop . Logs shows blm maxed out at 160 . Int max at 180 while cruising. The ECM is trying to correct this condition and probably squirting lots of fuel . What is your fuel pressure and injector size? In fact, can you provide the specs of your truck? Engine size. Cam, trans, exhaust etc...
Coolant temp never exceeds 75c (167f). What temp thermostat are you running? I recommend a 195f or at the very least 185f thermostat


check the voltage problem first . It could be simple, like the ECM is not grounded properly. And then address the fuel problem in close loop

 

[Heckelbone]

The end of that log is where the thing died in traffic. The spikes are me trying to restart it.

I don't follow when you say that the o2 sensor looks fine. Most of the time is is <100mv.
That would mean it's running lean, no? I made a mistake when I mentioned Rich above....because I have to clean my plugs.

I am at 40psi with 19# injectors.
345 with stock cam and pistons, triple y headers, and I have the manual tranny, t13 I think.

Yes, I have a cool thermostat, I will get the 195f asap.
I will verify proper grounding.

I know I'll have the take all the plugs out an clean 'em....they'll be sooty.

Thanks...

 

[ldo_marlin]

Assuming you don't have a problem with voltage.

I think your o2 sensor is working. The blms are very high (lean) at close loop. At idle open loop your o2 sensor value is in range ( around 410-440 mv) . I think the ranges are: under 300mv is a lean condition and above 600mv is Rich. In close loop the o2 sensor is reading very lean(low) and the blm also shows very lean. You can increase the injector flow rate to see if this will help. In tunerrt the injector flow rate is set at 18.99 now. Try changing to 18.5 (yes lower means more flow) . Change .5 at at time to see if the blm gets closer to 128 and o2 sensor voltage increases. The ECM will try to get close to blm 128 and you are so far from 128 that it will push lots of fuel trying to get to 128 (int)

however, this does not explain why your engine dies. No error flags, o2 sensor giving voltage, ECM in close loop..... When the engine dies. What ignition components are you running (distributor, GM e-core coil, GM ignition module ?).does the engine not want to start after it dies? Does it start after cool down? Can you describe more?

 

[Heckelbone]

what ignition components are you running (distributor, GM e-core coil, GM ignition module ?).does the engine not want to start after it dies? Does it start after cool down? Can you describe more?

Gotta lookup the disti... Afi system.
Promaster coil - 29440

before the plugs are fouled it runs well. Slowly gets worse hesitation, missing, loss of power; until it can't idle and dies in traffic. Once the plugs are goo'd it won't go at all.

I'll try the 18.5#

22 miles on these plugs...

 

[ldo_marlin]

So your engines dies from the plugs fouling and it will not ignite. And you have to clean or change the plugs for it to run again.....

Change the injector flow rate and try to get close to 128. Preferably right under 128 (slightly Rich). You are currently very lean in close loop

I am assuming you are using a GM conversion dizzy (bottom IH with GM top)? The promaster coil is a GM e-core equivalent? Can you post a picture if the dizzy and the coil?

 

[Heckelbone]

Yes, precisely.

I will clean the plugs and adjust the injector flow rate so that the blm hovers just below 128.

Thank you...

 

[ldo_marlin]

I think you have another problem with the promaster coil. I think that coil is not made to be used with a GM TBI/tpi ignition module. Ignition modules and coil work as a matched unit . There is an ohms requirement between coil and module for the unit to be able to put out the intended spark voltage and current . Swap the coil out for a GM e-core type (for TBI or tpi application). Cheap and available everywhere.

Just brief reading of what's available on the web about that mallory coil says it's made to work with points type ignition or a hyfire ignition module. The coil is probably not putting out enough current to keep the plugs from fouling.

Is this a new install? Or have you been running this mpfi set up and now having problems.

 

[Heckelbone]

It has been in 18 months. In that time I've replaced most of the moving or shiny parts. It never was dialed in and it still a work in progress.

Cool thanks guys, this is helpful. I will get these things done over the next few days and report back.

Coil specs :
part number: maa-29440
coil wire attachment: male/hei
coil style: canister
primary resistance: 0.600 ohms
coil internal construction: oil-filled
coil color: black
maximum voltage: 55,000 v
turns ratio: 105:1
secondary resistance: 12.3k ohms
inductance: 7.3 mh
peak current: 100 ma
spark duration: 500 us
mounting bracket included: yes
coil wire included: no
ballast resistor included: yes
coil shape: square
height (in): 5.297 in.
Length (in): 3.706 in.
Width (in): 3.846 in.

 

[Heckelbone]

I cleaned my plugs, thing barely runs. I will wait for the new coil, due in tomorrow.
I got the a mallory 30625 coil. Specs look okay?

 

[ldo_marlin]

I am not familiar with that coil. Not saying it will not work.

Mallory coil 29210 is the one I would use. Looks to be the same as msd 8226. Direct replacement for GM est application (TBI/tpi). The ignition module you're using is referred to as est (electronic spark timing). You'll need the TBI/tpi harness to plug in the coil.

Just for comparison. Look at the primary and secondary resistance specs for msd 8226 and mallory 29440 . Msd is a direct replacement coil for GM TBI/tpi application.

Can you describe "barely runs". How does it idle in open loop ? And it barely runs in close loop?

 

[Heckelbone]

Thanks for the info.

By barely runs, I mean it acts as if it's running on two cylinders, or like I hooked up all the plug wires wrong.
It does not smooth out with throttle, just gets worse.

 

[Eric VanBuren]

First off those look like champion plugs, if so can them and get some autolite or ac, the champions like to foul out and won't self clean.

If it sounds like its not running on all cyls you need to get that sorted out first, before attempting to tune the fuel. If a cyl doesn't fire the oxygen from that cyl will be pumped straight into the exhaust. All that oxygen in the exhaust will be read as a lean condition by the o2 sensor and max out the blms no matter what you do with the fuel.

 

[Heckelbone]

They are bosch. As long as I have to take them out to clean them, I might as well try the ac or autolite. Will do and report back.
Thanks.