Bad knock, running lean, and coolant temperature issues. - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


Pontiac When starting new posts, please specify YEAR, MAKE, MODEL, ENGINE type, and whatever modifications you have made.

Reply
 
 
 
Thread Tools Search this Thread
Old 05-18-2014, 11:15 PM   #1
Senior Member
Posts like a Turbo
Thread Starter
 
LoveNutz's Avatar
 
Join Date: Mar 2011
Location: Rochester, NY
Posts: 261
Thanks: 0
Thanked 0 Times in 0 Posts
LoveNutz is on a distinguished road
Default Bad knock, running lean, and coolant temperature issues.

Okay I don't really know where too start. I started having these at the beginning of last winter, and I'm not sure what'* going on. The first two are related. The engine is running lean. I swapped back to the stock air box at the beginner of the summer, but it is still too lean. I changed all the plugs, wires, and o2 sensor and still, nothing. I think this is causing the engine to knock.
When driving on the highway, if I put any boost on the engine at all, it will start knocking. Like, if I try to pass someone or go up a hill, my engine sounds like a rattle can and there is an obvious lack of power. Im getting readings of around 3 to 8 degrees.

I don't know why it'* running lean. Is it not getting enough fuel, or something else?

As for the coolant temp issue, this one has really got me stumped. Every cold start the engine heats up to around 225* then quickly drops down to around 188*. Then it usually hovers around normal operating temp. Of course the temp can't change that drastically that fast, so could it be a wacky sensor? I had a shop do a pressure test and they found a leaky water pump, so that and the thermostat have been replaced, but there is still a small leak somewhere.
LoveNutz is offline   Reply With Quote
Old 05-19-2014, 12:09 AM   #2
Senior Member
True Car Nut
 
rjolly87's Avatar
 
Join Date: Jun 2003
Location: Las Cruces, NM
Posts: 6,855
Thanked 298 Times in 246 Posts
rjolly87 has a brilliant futurerjolly87 has a brilliant futurerjolly87 has a brilliant futurerjolly87 has a brilliant futurerjolly87 has a brilliant futurerjolly87 has a brilliant futurerjolly87 has a brilliant futurerjolly87 has a brilliant futurerjolly87 has a brilliant futurerjolly87 has a brilliant futurerjolly87 has a brilliant future
Default

You need to fix the lean issue fast, because it can cost you an engine. Lean means that there is not enough fuel in the mix, so you will want to check for fuel delivery issues and vacuum leaks.

The second concern may simply be an air bubble stuck in the cooling system, or a sticking thermostat.
rjolly87 is offline   Reply With Quote
Old 05-19-2014, 07:30 AM   #3
Senior Member
True Car Nut
 
jwfirebird's Avatar
 
Join Date: Dec 2009
Location: western,ny state
Posts: 9,616
Thanked 563 Times in 481 Posts
jwfirebird has a reputation beyond reputejwfirebird has a reputation beyond reputejwfirebird has a reputation beyond reputejwfirebird has a reputation beyond reputejwfirebird has a reputation beyond reputejwfirebird has a reputation beyond reputejwfirebird has a reputation beyond reputejwfirebird has a reputation beyond reputejwfirebird has a reputation beyond reputejwfirebird has a reputation beyond reputejwfirebird has a reputation beyond repute
Default

your fueling is based on your temp so if you have a flakey ect it will effect all those other things. are you missing coolant at all, the other thing that comes to mind is lower intake gaskets. thermostat might be sticky too
jwfirebird is offline   Reply With Quote
Old 05-19-2014, 08:44 AM   #4
Senior Member

Certified GM nut
 
Tech II's Avatar
 
Join Date: Feb 2014
Location: Worcester, Ma.
Posts: 2,143
Thanked 780 Times in 609 Posts
Tech II has a reputation beyond reputeTech II has a reputation beyond reputeTech II has a reputation beyond reputeTech II has a reputation beyond reputeTech II has a reputation beyond reputeTech II has a reputation beyond reputeTech II has a reputation beyond reputeTech II has a reputation beyond reputeTech II has a reputation beyond reputeTech II has a reputation beyond reputeTech II has a reputation beyond repute
Default

How do you know it'* running lean?

Were any codes set?

Is it knocking or misfiring?

Are you losing coolant?
Tech II is offline   Reply With Quote
Old 05-19-2014, 08:49 AM   #5
Senior Administrator








Certified Car Nut
 
Mike's Avatar
 
Join Date: Jul 2003
Location: Horseheads, NY
Posts: 15,643
Thanked 997 Times in 774 Posts
Mike has a reputation beyond reputeMike has a reputation beyond reputeMike has a reputation beyond reputeMike has a reputation beyond reputeMike has a reputation beyond reputeMike has a reputation beyond reputeMike has a reputation beyond reputeMike has a reputation beyond reputeMike has a reputation beyond reputeMike has a reputation beyond reputeMike has a reputation beyond repute
Default

Get a fuel pressure gauge and run it up to your windshield under the hood in such a way that you can see the gauge while driving. You need to see the pressure peak under severe load.

I don't think his 188 temp is causing any issues. These computers are designed to go into closed loop after 160* anyway. My car will do the same thing and I run a 180 t-stat. During cold run, it will gradually warm up to just about 200*, drop down to 180 and stay there the rest of the trip.

Oh, and have you tried cleaning your MAF?
Mike is offline   Reply With Quote
Old 05-21-2014, 01:20 AM   #6
Senior Member
Posts like a Turbo
Thread Starter
 
LoveNutz's Avatar
 
Join Date: Mar 2011
Location: Rochester, NY
Posts: 261
Thanks: 0
Thanked 0 Times in 0 Posts
LoveNutz is on a distinguished road
Default

I cleaned my MAF when I put the stock air box back on and I changed the thermostat with the the water pump. As for codes, I haven't got a lean code since I took the the K&N out of the fender, but the two shops I took it to told me it was still running lean. The plugs looked really lean too.

I'm getting up to 8* of knock retard with just a little bit of boost.

I want to check for vacuum leaks, but I'm not sure how to do that.

And Mike, do you know of any way to check fuel pressure with the aeroforce gauge? I'll look at the manual later (if I can find it), but maybe you know?
LoveNutz is offline   Reply With Quote
Old 05-21-2014, 05:45 AM   #7
Senior Administrator








Certified Car Nut
 
Mike's Avatar
 
Join Date: Jul 2003
Location: Horseheads, NY
Posts: 15,643
Thanked 997 Times in 774 Posts
Mike has a reputation beyond reputeMike has a reputation beyond reputeMike has a reputation beyond reputeMike has a reputation beyond reputeMike has a reputation beyond reputeMike has a reputation beyond reputeMike has a reputation beyond reputeMike has a reputation beyond reputeMike has a reputation beyond reputeMike has a reputation beyond reputeMike has a reputation beyond repute
Default

No, not on a 98 system. Some of the newer luxurious cars have the built in sensors.
Mike is offline   Reply With Quote
Old 05-21-2014, 08:05 AM   #8
Senior Member
True Car Nut
 
jwfirebird's Avatar
 
Join Date: Dec 2009
Location: western,ny state
Posts: 9,616
Thanked 563 Times in 481 Posts
jwfirebird has a reputation beyond reputejwfirebird has a reputation beyond reputejwfirebird has a reputation beyond reputejwfirebird has a reputation beyond reputejwfirebird has a reputation beyond reputejwfirebird has a reputation beyond reputejwfirebird has a reputation beyond reputejwfirebird has a reputation beyond reputejwfirebird has a reputation beyond reputejwfirebird has a reputation beyond reputejwfirebird has a reputation beyond repute
Default

the parts stores have free rental for pressure gauges
jwfirebird is offline   Reply With Quote
Old 05-28-2014, 12:10 PM   #9
Senior Member
Posts like a Turbo
Thread Starter
 
LoveNutz's Avatar
 
Join Date: Mar 2011
Location: Rochester, NY
Posts: 261
Thanks: 0
Thanked 0 Times in 0 Posts
LoveNutz is on a distinguished road
Default

Okay, I'll have to take it too a shop or rent one soon because it'* only getting worse. I'm now getting a near constant knock around 1-3* driving on the highway. Idk if it was the fuel I put in or what?

As I'm typing this I realize that it'* probably better for me to take it to a shop. Have them check the injectors and look for vacuum leaks... Man, this is really bumming out. : (
LoveNutz is offline   Reply With Quote
Old 05-28-2014, 12:23 PM   #10
Senior Member
True Car Nut
 
jwfirebird's Avatar
 
Join Date: Dec 2009
Location: western,ny state
Posts: 9,616
Thanked 563 Times in 481 Posts
jwfirebird has a reputation beyond reputejwfirebird has a reputation beyond reputejwfirebird has a reputation beyond reputejwfirebird has a reputation beyond reputejwfirebird has a reputation beyond reputejwfirebird has a reputation beyond reputejwfirebird has a reputation beyond reputejwfirebird has a reputation beyond reputejwfirebird has a reputation beyond reputejwfirebird has a reputation beyond reputejwfirebird has a reputation beyond repute
Default

what does your fuel trim look like
jwfirebird is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
Bad, bad, bad, bad vibrations.... SilverSleeper8704 2000-2005 11 07-30-2010 06:42 AM
UPDATE - Multiple Cylinder Miss/Running Lean/Rough Idle Daron97SSE 1992-1999 7 05-05-2005 01:24 PM
running lean?? 1993 SLE 1992-1999 15 11-26-2004 10:46 PM
knock knock knock L27Buick 1992-1999 7 09-17-2004 04:23 PM
Knock Knock, engine knock? Spiral 1992-1999 5 05-23-2004 10:08 PM


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -4. The time now is 07:48 AM.


We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.