91 Z34 still Sick, but now have free scan

[robertisaar]

ALL LQ1s have a FPR that references manifold vacuum.

the pressure jumping as the engine dies is likely the FPR dialing up more pressure since the vacuum in the intake is equal to atmospheric.

the O2 isn't changing since it isn't getting up to a high enough temp to start switching. the only voltage it's showing is the reference voltage from the PCM.

[portsider44]

Ok here is my first uploaded tuner pro RT file. Thanks to Robert I got it figured out to some extent. THis is my second scan of the day so this not from cold start. I had another scan running thinking I was logging but was not. During the first run it stalled several times & I did quite a bit of crankning. So the non running battery volts may seem low.

I still have my FP gauge mount & its been on there over a week. funny thing is pressure has gone up a few psi from the first day I attached. I did pull vac line to map from FPR & had no smell of gas.

Somethings I wonder if it will run for every if I don't mess with it? While the idle is not real smooth it appears it would just keep going. However when I bring RPM up it causes the stall. During the RPM increase fuel pressure drops 2-4 psi & once the stall happen it shoot up 3-6psi. If the fuel pump or FPR were bad would I see a bit drop if they were the cause?

When it stalls there is no stumble just goes from lets say 2000 RPM to dead in a split second. Which to me seems more electrial vs lack of fuel. My GN when I would kill the fuel Pump car would spit & sputter before dying with lack of fuel.

Also I notice when it stalls if I try to restart right away it wont, but if I pause 4-6 seconds it will but you have to give it gas to keep running. During the wait time I can hear the fuel pump run just as it does when you first turn the key on.

Also keep in mind my cat is not clogged, & I still have a problem with the trans not wanting to shift into low gear doubt this is related but just in case.

**having problems uploading file will try again

[robertisaar]

no file attached...

[portsider44]

FInally got it to go it appears try number 15 was the magic number

[robertisaar]

ok, a few things i notice... MAP seems fairly accurate(or at least believable), though though i'm not sure what kind of elevation you're at to be pulling a ~91kPa barometric number, though it later changed to 94...

your TPS is all over the place at times, but it looks like you were pumping the pedal, but then i look at samples ~4004 to 4038, where you held the throttle perfectly still, but you went from a fairly smooth 1550RPM at 44kPa high idle to a stall...

it is also odd that you NEVER hit closed loop(or at least BLM Enable), even though you should have multiple times. from the looks of it, the O2 is just BARELY swinging, which is what it does when either cold or junk.

it seems to idle with a lot of IAC steps as well.... not sure what that's indicating though, but my suspicion is that it's idling VERY rich, basically dousing the O2 and not letting it get warmed up, which happens to require more air due to an engine not being very efficient when running extremely rich. what do the spark plugs look like?

[portsider44]

ok, a few things i notice... MAP seems fairly accurate(or at least believable), though though i'm not sure what kind of elevation you're at to be pulling a ~91kPa barometric number, though it later changed to 94...

In Lubbock TX, elevation 3200 ft

your TPS is all over the place at times, but it looks like you were pumping the pedal, but then i look at samples ~4004 to 4038, where you held the throttle perfectly still, but you went from a fairly smooth 1550RPM at 44kPa high idle to a stall...

I think this was just me, car idled for sometime & then I increased idle to see what would happen. In this case it stayed at 1500 range sounded decent & then just died at line 4027. From 4028-4040 tps numbers caused by it dying & me still haveing the petal depressed.

it is also odd that you NEVER hit closed loop(or at least BLM Enable), even though you should have multiple times. from the looks of it, the O2 is just BARELY swinging, which is what it does when either cold or junk.

which colum shows this? would a faulty ecm cause it not to go into open loop?

it seems to idle with a lot of IAC steps as well.... not sure what that's indicating though, but my suspicion is that it's idling VERY rich, basically dousing the O2 and not letting it get warmed up, which happens to require more air due to an engine not being very efficient when running extremely rich. what do the spark plugs look like?

plugs ar black, so it must be rich. Just not sure where the safest place to spend money next. COuld a faulty fuel pump cause it to be rich? If the fuel pump relay was bad would it cause the fule pump volts to drop when it acted up? Also seems if it was a sensor we would see it take a nose dive during stall.

COuld it be a faulty ecm & everytime it tries to come out of closed loop into open loop it stalls? ALso if my new crank position was faulty would it shows on the scan?

[robertisaar]

http://www.altitude.org/air_pressure.php

3200 feet comes right out to 91kPa, so that's fine.

the O2 voltage shows how it's just barely moving away from the .45Volt reference the PCM is giving it. a bad PCM COULD cause issues like this, but let's explore cheaper options first.

blck plugs, yeah, that's rich alright. a bad fuel pump would likely show as being VERY lean, not rich. relay is also not suspect. considering the fuel pressure you're seeing at idle, i'd like to say the fuel pressure regulator is going bad. do you have a vacuum pump? if so, when it's idling, pull the FPR line and keep applying vacuum and see if you get it to act normally.

if the crank sensor was bad, then you wouldn't even get fuel injectors firing or spark, since that's the only way the PCM can read the speed of the engine and the ICM reading the position of the engine.

[portsider44]

Sorry for delay run another scan yesterday but never could get it to upload. If you will notice on the scan there are chunks of the scan that are missing, as I deleted them to shirnk the size of the report (thought the size was upload issue). On this scan I let it idle for over 10 mintues.

Longer it idled the closer it got to the computer desired idle. O2 volts were steady but low & it was still running rich. Fuel pressure was 45psi key on & 42-45psi at idle. I felt like it would have idle all day, however the minute I gave it gas it died.

I don't have a vacuum pump by I might be able to borrow one, I will work on that.

**also it never went to closed loop even though coolant temp was over 180, I guess this was due to low O2 volts.

[robertisaar]

42-45 at idle is wrong.

[portsider44]

I am starting to have my doubts about how accuarte my FP gauage is. Bought a cheapie at Harbor Freight & first time out of the box it showed 40psi key on not running & 38psi when idle. Now after having it attached to the car for 2 weeks it reading about 5psi higher.

I will pull it off & test it on my truck & see how it looks there.

"pull the FPR line and keep applying vacuum and see if you get it to act normally." I guess you mean to pull the vacuum line that goes from MAP to FPR & then hook vauum pump up to FPR & leave the MAP disconnected? do I need to plug it?

Still puzzled by the constant/mostly normal looking sensor readings when running & when it stalls. Plus the whole ability to idle with no issue but dies quickly once RPM increased.

If the filter or fuel pickup sock were clogged or collasping under load could it still have good PSI on gauge yet not deliver the fuel?

[robertisaar]

if it wasn't delivering enough fuel, the pressure would drop considerably.

to test the FPR, pull whatever vacuum line it is that goes to it, hook up a pump, and then use the little fuel pump priming lead near your left strut tower to force the fuel pump on. then apply various amounts of vacuum to see if it changes pressure at the fuel rail. that takes the motor itself out of the equation and tests just the FPR.

[portsider44]

What should my vacuum be idling? It running at 14-11 idling testing at MAP where FPR hooks up. Sign of vacuum leak?

Also hooking vacuum pump up & putting 15lbs of vaccum brings FP down to 38-39lbs key on not running & 41-43 idling.
Pluging map sensor where FPR hooks up & hooking up to FPR & pulling vacuum on it did help to get my 02 number into the 560-590 range but no higher.

Will post tunerpro file later, time to pick up the kids

[robertisaar]

560-590 is a little above stoich.... assuming the O2 was hit enough when read.

and specs for the fuel pressure test are:

no vaccum applied: 43.5PSI
10" of mercury should bring it down by 3-10PSI

seeing how you applied 15", and only got from 2-5, i would like to think the FPR is an issue.

and i'm not quite sure where a LQ1 should idle at in refernce to how much vacuum.... but 11 has to be too low... that's roughly 60kPa absolute, the power brake booster would have a VERY hard time.

[portsider44]

is there a secret to uploading files, everytime I try to upload I have problems. Is there size restrictions?

messing with this car is trying enough, so I really could use some things to go easy

[portsider44]

tuner pro 4.xls

I went in I cut the file down so look at line item to see where parts were cut out