Blms in 90s, can't go past 1/4 throttle???

[fullahotair]

oh yeah...WOT TPS... I believe it is still in power enrichment mode at value...i could be wrong... i need look back and see for sure...


Nate

 

[fullahotair]

The only thing that jumps out at me.... is looking at the datalog 062308C.dat

Get to the area where the TPS is the highest... still not WOT... but close (4.23 v on the TPS)...

Examine the 02 volts... and the Injector pulse width at the same time..... the 02's are in the 800's there... and the pulsewidth is showing....32.69..... a frame or two later.... 02's drop to .027 volts... and the pulsewidth has actually increased to 38.50.

This makes no sense... If the FP is there.... and the pulsewidth hasn't drastically changed.... 02's shouldn't drop from .811 to .027........

It appears to me you might be having some sporadic issues with the 02 sensor.... as long as you are confident that the FP is still good when this takes place... during this run....

For my own education here, let me see if I understand the logic and ask a few questions... I am not fully versed on pulse width what it should read/do..

1. If you lose fuel pressure, would the pulse width go up to compensate?? Longer pulse = longer time it injects full = more fuel?

2. At WOT throttle (power enrichment), the 02 should stay relatively steady right? hmm i wonder why it drop to .027? bad 02 connection? Do you ever see your 02's go to zero (not at WOT), I have observed this....


thanks guys for trying to help out... I'll keep troubleshooting...

Nate

 

[notacarlo]

Try to cycle your fuel pump. Keep it running for 30 seconds. Watch fuel pressure. You can jump the pump via little green or gray wire on drivers side near the valve covers. I think the gray might be tach......can't remember. Other end to a 12 volt source.

If your 02's are dropping off like that it could be the pump.....but.....if the ecm doesn't see the need for fuel the 02's will drop in relation to throttle position.

 

[Blazer406]

For my own education here, let me see if I understand the logic and ask a few questions... I am not fully versed on pulse width what it should read/do..

1. If you lose fuel pressure, would the pulse width go up to compensate?? Longer pulse = longer time it injects full = more fuel?

2. At WOT throttle (power enrichment), the 02 should stay relatively steady right? hmm i wonder why it drop to .027? bad 02 connection? Do you ever see your 02's go to zero (not at WOT), I have observed this....


thanks guys for trying to help out... I'll keep troubleshooting...

Nate

1.) It will only compensate at WOT... if you have a wideband controlled chip setup. The factory setup... ignores the 02 at WOT and goes off whatever pulsewidths were programmed into that portion of the table..... I assumed yours was not wideband controlled.

2.) Yes... 02's shouldn't move around alot at WOT.... especially not from .811 all the way to .027. That could definately cause a lean pop... or stumble.... and eventually a hurt motor...

At part throttle.... the 02's fluctuate around 450 mv.... which is close to 14.7:1.... they go up and down like a yo-yo centered around .450 mv..... when it goes above 450... the ecu sees this as a slight rich condition.. and pulls a slight amount of fuel.....then it falls below .450.... this triggers a slight lean condition.... to which the ECU adds a little fuel. Each time the 02's pass that key .450 mV line.... it increases the "cross counts" by one.... this value is something to look at when cruising in closed loop... a good 02 sensor.... will be quick to show any little changes... so you will see the cross counts very active.... they start at 1... and increment to 255.... then start back over at one...... a lazy 02.... will be real slow to increment the cross count number... or won't increment at all...

In your case.... because the pulsewidth changed very little... yet the bottom fell out of the 02's.... leads me to think fuel pressure problem.... or 02 problem..... and I am leaning toward fuel pressure problem.... because it did stumble/pop/whatever.... and the 02's confirmed a sudden lean condition enought so to cause a pop......... just something to confirm...

HTH

 

[fullahotair]

What results would you expect to see when you cycle the fuel pump for 30 seconds? Should the fuel pressure stay at 45 psi or whatever for that duration? If I plum a fuel line so i can read it while driving, (if it was the fuel pump), would i expect it to drop to near zero and then back up when it is breaking up??

So if you (we) are thinking the fuel pump... can a fuel pump problem be intermittent? What would cause a fuel pump to work for one sec, and then not another?? hmm...maybe i'll pull off the new fuel filter and see if there is crap in it?


As always...thanks!

Nate

 

[Blazer406]

A fuel pump relay or contacts in the electrical system between battery and fuel pump.....could be making the pump cut on and off.... see the FP is under the most strain when it is trying to deliver a high volume at a high pressure....this is fairly hard to replicate sitting still..... cause you cant be WOT under boost for very long.... a good 3rd gear blast with a fuel pressure gauge where (preferrably a passenger) can read it... might show you if the pressure is going nuts...

 

[fullahotair]

Ok cool, I'll make an extentsion for the Fuel pressure guage tonight and get near the windshield so we can observe it so we can rule it in or out for good!!!

...i'll report back...


Thanks
Nate

 

[notacarlo]

My suggestion was to listen to the pump(though I did not clarify). If it sounded intermittent, racy, anything other than a constant hum I would say there's a pump issue.

As far as the relay goes, in my experience when they go....they go. Never intermittent. I do not suspect the relay at this time. I do think there might be a pump issue though.

You can use the gauge to make sure you have a constant pressure - if it fluctuates a lot....there's a problem for sure.

I tend to operate on the look,listen,feel approach. It's how I found my wife.:biggrin:

 

[bmackinnon]

Keeping it simple.... NEW MAF, T+, Chip, Injectors leads me to suspect these new players first, probably the MAF/T+ combo setup, especially with that new integrated pipe/sensor deal from FT. That said, probably 50% of these 'runs fine until it starts to go to boost' deals end up being the coil pack/ign. module... got a Casper's tester anywhere handy?

 

[fullahotair]

it is also a new fuel pump......

I checked the coil pack, the ohms fall with in spec hot and cold... Does the casper's tool check something else? How can you test the ign. module? or is that what the casper's tool does?

Thanks,
Nate

 

[bmackinnon]

it is also a new fuel pump......

I checked the coil pack, the ohms fall with in spec hot and cold... Does the casper's tool check something else? How can you test the ign. module? or is that what the casper's tool does?

Thanks,
Nate

Yup... checks the CP/IM combo as a whole... under load. Don't know of any other way to test the IM. Any friends around you could you could borrow one from to swap for a known good one?

 

[fullahotair]

In this PL file : 062308D , (link to the fullthrottletech page is above)

spark advance is fluctuating all over ...during the break up...can that be correlating to anything? or would that be expected if the fuel pump is an issue?

Thanks,
Nate

 

[bmackinnon]

In this PL file : 062308D , (link to the fullthrottletech page is above)

spark advance is fluctuating all over ...during the break up...can that be correlating to anything? or would that be expected if the fuel pump is an issue?

Thanks,
Nate

Sorry, just a lowly Directscan user here... :tongue: Probably hard to say which came first... like the chicken and the egg.... funny things in the logs causing or resulting from the breakup. Maybe the same w/ the O2's and PW's. Check and make sure the pos. batt. cable is nowhere near contacting a header or other short, causing electrical problems when you start to 'get on it'. Seen it (well, read about it) MANY times....

 

[TurboDave]

In this PL file : 062308D , (link to the fullthrottletech page is above)

spark advance is fluctuating all over ...during the break up...can that be correlating to anything? or would that be expected if the fuel pump is an issue?

Thanks,
Nate

You need to beg/borrow/steal a known good ignition/coil module assembly for troubleshooting purposes.

 

[fullahotair]

You need to beg/borrow/steal a known good ignition/coil module assembly for troubleshooting purposes.

LOL...i'll see what I can come up with... I know where there is a GN sitting, but the problem is i doubt i (or the owner) would be able to say i KNOW it is good.

In the mean time i'll rule out the fuel pressure...


Thanks,
Nate

 

[fullahotair]

Unplugged the ECM, reset the chip to make sure the contacts were good.

Made a remote fuel pressure guage so i could see what was happening when the car was breaking up. Fuel pressure stayed pretty consistent, I might blip a psi or two, but i would attribute that small amount to the engine cutting in and out...


A general observation tonight, was my first run (wish i recorded it) felt pretty darn good...I was able to to go essentially WOT (i didn't go flat out, as i wanted to ease into WOT, to watch for knock)...subsequents runs were crap, couldn't get to WOT with it out cutting out, and the occasional backfire/pop. This was also generally the case last night too... hmmm my non scientific assessment makes me wonder if the coil pack/module is getting hot and breaking up under load and heat....


Nate

 

[Blazer406]

... hmmm my non scientific assessment makes me wonder if the coil pack/module is getting hot and breaking up under load and heat....


Nate

Bingo....

I think you are on to something.

When mine died.... I read all the horror stories about buying a non-GM module.... so my budget led me to go to the junkyard and buy a type II coilpack and module. They are IMHO.... "easier" to find a good one... than the magnivox unit that came on our cars....I would prefer the stock look of a Magnivox.... but haven't needed to replace my $40 junkyard coilpack/module combo yet.....

 

[notacarlo]

Half way down the page is the coil tower resistance.

Quick Reference Page For the '86/'87 Turbo Regals and '89 Turbo T/A

This will allow you to test the coil.

 

[fullahotair]

I have already tested the coils cold and hot...all the readings were in spec...but i guess that doesn't duplicate the load....

I'll have to do some research on those type II coil packs and ignition module...

Thanks for the ideas...i'll keep on chugging...

Nate

 

[Blazer406]

I have already tested the coils cold and hot...all the readings were in spec...but i guess that doesn't duplicate the load....

I'll have to do some research on those type II coil packs and ignition module...

Thanks for the ideas...i'll keep on chugging...

Nate

The Caspers tester will test it adequately.... however some if not all non-gm modules won't pass the casper's tester......I read....