HELP! Running terrible...can't find problem
06-30-2009, 12:12 PM
#1
Registered User
Thread Starter
Join Date: Apr 2005
Location: NY
Posts: 35
HELP! Running terrible...can't find problem
I have a 94 Impala SS that is running very bad. It chugs violently at idle as and has general loss in power all around. The problem started as an intermittent chug at idle but now it is almost all the time and also runs very bad at part/full throttle. Here is what I have done/checked
replaced opti with new Delphi unit
new plugs
new wires
swapped coil with my friends car and ignition module from my 96: didn't help
swapped 02 sensors from my 96
swapped IAC from my 96
swapped MAP from my 96
new coolant temp sensor
took off TB and cleaned it, new PCV valve (lots of oil build up)
No cats
EGR delete
Bryan H PCM-problem still persisted after hooking it up.
Fuel pressure is 38 at idle, over 45 at WOT and somewhere steady in the 40's (forget exactly where, I want to say mid-upper 40's) with the vacuum hose off. No fuel in vacuum hose.
Scanner is showing the bank 1 02 sensor at under 100mv. Right side is oscillating around 450 but leaning a little on the high side (BLM is 136 at idle, oddly enough the side with the lean 02 has a BLM of 128 WTF!). Once in a blue moon, the idle will clear up instantly for a few seconds and the 02 mV on that side will oscillate normally over and under 450 again.
Being that the bank 1 02 is showing VERY lean, I tried pulling each injector connector to see what happened. Cyl 7 made NO change in idle what-so-ever when pulling the injector connector and likewise 02 mV didn't change at all. I thought I had it narrowed down but here's what is strange. The plug to that injector doesn't look lean at all, it is gold, gap is fine. I replaced the injector with one a forum member gave to me but the problem persists. Oddly enough, that one injector has ohm'd out as low as one bad one I had before that was causing an idle misfire (12.5ish compared to most of the rest which are high 12's-low 13's). Don't know if this could be it though, it came off of a car that ran fine). Haven't had a chance to hook up a noid light on the cyl in question. Compression test on that cyl showed all was fine.
I am really hoping it's the injector wiring on that side but then WHAT is causing bank 2 to be so rich? And if bank 1 is showing under 100 mV all the time then why is that bank at a perfect 128 BLM?
Also, when I unplug the coolant temp sensor the car does not go into open loop. shouldn't it? I wanted to run it in open loop to rule out MAF and 02's, how can I do this if unplugging the CTS doesn't do it?
this is my daily driver and it's driving me crazy! I really need to fix it and soon. thanks in advance !
replaced opti with new Delphi unit
new plugs
new wires
swapped coil with my friends car and ignition module from my 96: didn't help
swapped 02 sensors from my 96
swapped IAC from my 96
swapped MAP from my 96
new coolant temp sensor
took off TB and cleaned it, new PCV valve (lots of oil build up)
No cats
EGR delete
Bryan H PCM-problem still persisted after hooking it up.
Fuel pressure is 38 at idle, over 45 at WOT and somewhere steady in the 40's (forget exactly where, I want to say mid-upper 40's) with the vacuum hose off. No fuel in vacuum hose.
Scanner is showing the bank 1 02 sensor at under 100mv. Right side is oscillating around 450 but leaning a little on the high side (BLM is 136 at idle, oddly enough the side with the lean 02 has a BLM of 128 WTF!). Once in a blue moon, the idle will clear up instantly for a few seconds and the 02 mV on that side will oscillate normally over and under 450 again.
Being that the bank 1 02 is showing VERY lean, I tried pulling each injector connector to see what happened. Cyl 7 made NO change in idle what-so-ever when pulling the injector connector and likewise 02 mV didn't change at all. I thought I had it narrowed down but here's what is strange. The plug to that injector doesn't look lean at all, it is gold, gap is fine. I replaced the injector with one a forum member gave to me but the problem persists. Oddly enough, that one injector has ohm'd out as low as one bad one I had before that was causing an idle misfire (12.5ish compared to most of the rest which are high 12's-low 13's). Don't know if this could be it though, it came off of a car that ran fine). Haven't had a chance to hook up a noid light on the cyl in question. Compression test on that cyl showed all was fine.
I am really hoping it's the injector wiring on that side but then WHAT is causing bank 2 to be so rich? And if bank 1 is showing under 100 mV all the time then why is that bank at a perfect 128 BLM?
Also, when I unplug the coolant temp sensor the car does not go into open loop. shouldn't it? I wanted to run it in open loop to rule out MAF and 02's, how can I do this if unplugging the CTS doesn't do it?
this is my daily driver and it's driving me crazy! I really need to fix it and soon. thanks in advance !
Last edited by SSandman; 06-30-2009 at 12:18 PM.
06-30-2009, 10:43 PM
#2
Registered User
Join Date: Mar 1999
Location: Kernersville, NC
Posts: 2,059
When you say it chugs at idle...is this under load in drive or sitting in park? Will it idle fine in neutral/park? Have you swapped your MAF? My wife's 2000 Nissan Maxima developed a problem with it's MAF one time and that thing bucked and chugged something fierce. Replaced it and it was gold after that...
You should be able to unplug the MAF to get the car to run in speed density. However....I've had trouble with that because when I unplug mine...I can't get the dang thing to start.
You should be able to unplug the MAF to get the car to run in speed density. However....I've had trouble with that because when I unplug mine...I can't get the dang thing to start.
Last edited by ACE1252; 06-30-2009 at 10:58 PM.
07-01-2009, 11:32 AM
#3
Registered User
Thread Starter
Join Date: Apr 2005
Location: NY
Posts: 35
It wont start with MAF unplugged but apparently with the ECT bypassed using a paper clip AND unplugging the MAF after you get it running the computer will go into speed density/openloop so no MAF and no 02 correction. MAF voltage looks good and I tried unplugging it while running and it made no difference....
The chug is as if one cyl just flat out isn't firing. you can hear it in the exhaust note, it's steady but loud and slow compared to the other side which is smooth and quick like it should be.
I think i narrowed it down to possibly a bad injector wire, as when the idle gets chug like and 02 mV drop, I unplug cyl 7's wiring and it makes NO difference. But on the rare occasion that the idle smooths out, I mess with the cyl 7 02 wiring and it often starts chugging again and 02 mV go from being where they should be to in the teens again.
What I DONT understand is why the bank with the chugging idle/02 Mv dipping into the teens ect... has a BLM of 128 and the OTHER side which seems to idle fine has a BLM of 136 ??!!
That throws a wrench into things, I am just hoping that fatigue set in and dumbness got the better of me....maybe I confused banks when reading the blm's on the scanner.
On top of this, I may have another problem. There is a stream of oil coming down the timing cover but I can't tell from where. I did the w/p drive seal, put it on dry, didn't stretch it too much, didn't fold the lip over ect... and i had no leaks for the 2 or 3 weeks I had the other opti/WP in, but now after doing a new opti/waterpump I am seeing oil and even getting a puddle in my driveway. What gives!!
The chug is as if one cyl just flat out isn't firing. you can hear it in the exhaust note, it's steady but loud and slow compared to the other side which is smooth and quick like it should be.
I think i narrowed it down to possibly a bad injector wire, as when the idle gets chug like and 02 mV drop, I unplug cyl 7's wiring and it makes NO difference. But on the rare occasion that the idle smooths out, I mess with the cyl 7 02 wiring and it often starts chugging again and 02 mV go from being where they should be to in the teens again.
What I DONT understand is why the bank with the chugging idle/02 Mv dipping into the teens ect... has a BLM of 128 and the OTHER side which seems to idle fine has a BLM of 136 ??!!
That throws a wrench into things, I am just hoping that fatigue set in and dumbness got the better of me....maybe I confused banks when reading the blm's on the scanner.
On top of this, I may have another problem. There is a stream of oil coming down the timing cover but I can't tell from where. I did the w/p drive seal, put it on dry, didn't stretch it too much, didn't fold the lip over ect... and i had no leaks for the 2 or 3 weeks I had the other opti/WP in, but now after doing a new opti/waterpump I am seeing oil and even getting a puddle in my driveway. What gives!!
Last edited by SSandman; 07-01-2009 at 11:40 AM.
07-01-2009, 11:44 PM
#6
Registered User
Thread Starter
Join Date: Apr 2005
Location: NY
Posts: 35
Well I found problem 1, but I think there is still something else going on...
I hooked up the noid light at work, wiggled injector wiring to cyl 7 and right up by the pigtail I could wiggle it slightly and the noid light would go out. I'd wiggle it so I can get the noid light to work again, then plug it in and 02 mV went from teens to oscillating somewhat normally above/under 450mv and the violent chug was gone...though it still sounded like it was misfiring SLIGHTLY (I am guessing still from that cylinder, maybe not getting full voltage to the injector?). so in short, either a break in the wire or loose connection at the pigtail was causing the injector to completely not fire...
I am hoping that once I fix this all will be well but the weird BLM's on the other side and the fact that even when that injector IS firing there is still a misfire and general lack of power makes me think there is more wrong, but fixing the wiring is a start and will also solve the biggest problem I am having with the violent chugging and really bad bouts of power loss.
As for the codes, nothing. Wish I had OBD2....I hate having such an obvious problem that the computer doesn't acknowledge....at least OBD2 would be showing me misfires or a lean code, I am guessing OBD1 has none of that.
No extension on the 02 harness, but someone did a hackjob at welding the hookup pipes together (cats deleted, hook up pipes that run to the shorties look like they were made from scrap metal). There are welds on the tailpipes that obviously leak as water sprays out, so if I keep getting blm problems after fixing the wiring im going to start checking the welds on the hookup pipes for leaks.
I hooked up the noid light at work, wiggled injector wiring to cyl 7 and right up by the pigtail I could wiggle it slightly and the noid light would go out. I'd wiggle it so I can get the noid light to work again, then plug it in and 02 mV went from teens to oscillating somewhat normally above/under 450mv and the violent chug was gone...though it still sounded like it was misfiring SLIGHTLY (I am guessing still from that cylinder, maybe not getting full voltage to the injector?). so in short, either a break in the wire or loose connection at the pigtail was causing the injector to completely not fire...
I am hoping that once I fix this all will be well but the weird BLM's on the other side and the fact that even when that injector IS firing there is still a misfire and general lack of power makes me think there is more wrong, but fixing the wiring is a start and will also solve the biggest problem I am having with the violent chugging and really bad bouts of power loss.
As for the codes, nothing. Wish I had OBD2....I hate having such an obvious problem that the computer doesn't acknowledge....at least OBD2 would be showing me misfires or a lean code, I am guessing OBD1 has none of that.
No extension on the 02 harness, but someone did a hackjob at welding the hookup pipes together (cats deleted, hook up pipes that run to the shorties look like they were made from scrap metal). There are welds on the tailpipes that obviously leak as water sprays out, so if I keep getting blm problems after fixing the wiring im going to start checking the welds on the hookup pipes for leaks.
Last edited by SSandman; 07-01-2009 at 11:47 PM.
07-02-2009, 12:11 AM
#7
Administrator
Join Date: Nov 1998
Location: Hell was full so they sent me to NJ
Posts: 70,669
OBD-I has codes for "lean" and for faulty injector circuits. That's why its hard to understand how there were no codes for a faulty injector wire. You should have had DTC 18. Same with the problem of the low O2 sensor reading. Should have set DTC 44 for Bank 1 lean.
http://shbox.com/1/Dtcs.htm
http://shbox.com/1/Dtcs.htm
07-02-2009, 11:55 AM
#8
Registered User
Thread Starter
Join Date: Apr 2005
Location: NY
Posts: 35
OBD-I has codes for "lean" and for faulty injector circuits. That's why its hard to understand how there were no codes for a faulty injector wire. You should have had DTC 18. Same with the problem of the low O2 sensor reading. Should have set DTC 44 for Bank 1 lean.
http://shbox.com/1/Dtcs.htm
http://shbox.com/1/Dtcs.htm
I still am not getting the whole BLM thing though. I mean I know for a FACT now that cyl 7 injector is having trouble, I know that sometimes it doesn't fire at all and it causes 02mV to go into the teens.... The BLM on that side shows 128, but when the problem starts acting up it will drop into the low 120's indicating the PCM is commanding LESS fuel...but why? If the injector doesn't fire, 02 mV shows in the teens and that cylinder is shooting out a straight shot of fresh air with no fuel...why would the computer be commanding LESS fuel, shouldn't it want to add more?
As for the code, I am pretty sure when I was pulling injector connectors off to test for changes in idle quality, I still dont think I got a code....hmmm
Last edited by SSandman; 07-02-2009 at 04:35 PM.
Thread
Thread Starter
Forum
Replies
Last Post
Sarahrope64
LT1 Based Engine Tech
0
11-27-2014 11:17 AM