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92 buick lesabre 3800 runs rich


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autotechnoob
Novice

Aug 14, 2010, 3:28 PM

Post #1 of 13 (4111 views)
post icon 92 buick lesabre 3800 runs rich Sign In

ok so i have a 92 buick lesabre 3800 with tuned port injection it has a rough idol, i know for a fact its running rich because i have hooked it up to a scan tool and it ran lean/rich back and forth for about 5 min then went straight rich with no codes. i know its not the o2 sensor(its been replaced) fuel pressure reads 40.7. vacuum pressure is fine and dandy between 17 to 18 hg. and to add ive checked injectors with a beep tester from snap-on and all injectors are firing. have also replaced maf sensor car is sluggish at acceleration is now jerking slightly on me now when going highway speed. so i need help asap running out of ideas and it my only mode of transportation. the only thing i can think of is it might be the iac valve any suggestions?


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Aug 14, 2010, 3:50 PM

Post #2 of 13 (4104 views)
Re: 92 buick lesabre 3800 runs rich Sign In

If it's not setting any rich codes, what makes you think it's running rich? I seriously doubt it.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



autotechnoob
Novice

Aug 14, 2010, 5:08 PM

Post #3 of 13 (4101 views)
Re: 92 buick lesabre 3800 runs rich Sign In

well the scan tool i used had lights for the rich/lean they blinked back and fourth and then it just stayed lit on rich but displayed no codes


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Aug 14, 2010, 5:14 PM

Post #4 of 13 (4098 views)
Re: 92 buick lesabre 3800 runs rich Sign In

I doubt it's really running rich. It will set a code as soon as the adaptives can no longer compensate for it. It was probably just the scan tool being unable to update the data fast enough.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



autotechnoob
Novice

Aug 14, 2010, 6:52 PM

Post #5 of 13 (4094 views)
Re: 92 buick lesabre 3800 runs rich Sign In

well if that is the case what else would make my cat burn up because it was just replaced and i had to take it out cause the honey comb got burnt up again and it was gettin clogged? could a cloged up muffler do that?


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Aug 14, 2010, 6:56 PM

Post #6 of 13 (4090 views)
Re: 92 buick lesabre 3800 runs rich Sign In

That makes no sense at all. Why would you gut out a new cat that was still under warranty?
Your car is not running rich. The ecm would set a code when it reached adaptive limits.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



autotechnoob
Novice

Aug 14, 2010, 7:13 PM

Post #7 of 13 (4087 views)
Re: 92 buick lesabre 3800 runs rich Sign In

ok well it wasnt under warranty cause i put it in myself and like i said its my only mode of transportation and i live out in the middle of the country so it would really suck to have my car break down on me in the middle of nowhere and i barley got home the night i took it out and it was burnt up and i didnt gut it i just put straight pipe in till i could get the problem fixed because i do go to college for automotive technology so im kinda broke cant afford to buy a new one quite yet and my teachers wont help unless its ford product for some reason. so now im out of ideas which is why im resulting to fourms. and its not just that scan tool either ive used a few (snap on, an actual gm obd1, my cheap one from napa) and none come up with codes so if you have any other possible ideas im all open ears.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Aug 14, 2010, 7:20 PM

Post #8 of 13 (4080 views)
Re: 92 buick lesabre 3800 runs rich Sign In

I don't know what it is that your trying to fix. Even if it was running rich, that wouldn't take out the cat. Raw fuel, heavy oil consumption or coolant are the things that plug up converters. It would have to be blowing black smoke for a very long time to take out the cat. Other than your idea that it's running rich, I haven't read any other issues or symptoms.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



autotechnoob
Novice

Aug 14, 2010, 7:35 PM

Post #9 of 13 (4076 views)
Re: 92 buick lesabre 3800 runs rich Sign In

well it has been using large ammounts of fuel after i started having problems with it i was getting 340 -360 miles to the tank now i get about 200 if im lucky and its all highway. and my oil gradually has been getting lost so idk every one seems to not know so im just looking for anything that might help send me in the right direction and im stubborn i wont let some one else work on my vehicle plus if im going to make it in this field i need to figure it out


autotechnoob
Novice

Aug 14, 2010, 7:43 PM

Post #10 of 13 (4072 views)
Re: 92 buick lesabre 3800 runs rich Sign In

also if it isnt hard enough to tell no black smoke


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Aug 14, 2010, 7:43 PM

Post #11 of 13 (4072 views)
Re: 92 buick lesabre 3800 runs rich Sign In

Your going to have to examine the sensor data more closely. If you have the ability for customer data, delete everything but O/2 readings, Integrator and block learn and injector pulse width.
You need to look for a pattern where the o/2s go rich. When you see that look to see what the injector pulse width does along with the block learn. On block learn, 123 is center, anything lower is leaner and anything higher is richer. See what they are doing to be avblle to determine what really is happening here. You could have a bad ECM that is going rich and doesn't know it.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



autotechnoob
Novice

Aug 14, 2010, 7:54 PM

Post #12 of 13 (4067 views)
Re: 92 buick lesabre 3800 runs rich Sign In

ok come monday ill be able to get ahold of a scan tool again and thank you for your help ill repost when i find something but if it is the pcm im gonna be pissed cause its been replaced twice and im gonna have to raise hell with some people


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Aug 14, 2010, 7:58 PM

Post #13 of 13 (4063 views)
Re: 92 buick lesabre 3800 runs rich Sign In

If things start pointing toward an ECM, then you'll have to start checking all the grounds for the ECM. I have seen a bad ECM ground act like that. Get a pinout diagram and verify all the grounds but only if these tests start pointing to a bad ECM.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.







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