Intake Air Sensor Woes?
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raykinsella
- Posts: 82
- Joined: Thu Sep 14, 2006 6:36 pm
Well I reinstalled my used AFM and bent that little rod so the contacts weren't touching when the engine was off, and - hey! - the pump no longer turns on with the key. Thanks, Wildthings!
The car runs great with the used AFM. I pried off the lid to the internals of the new/rebuilt one I just got and saw that the insides did not look as good as the repainted outside. A bit worn along the slider, but nothing broken. Can't tell anything about its settings just looking at it, but the idle screw under the rubber plug was turned way "up" in the hole compared to the one on my original unit. I wonder if a shop can set the settings on my new AFM without it being in the car, if I were to just bring it in...
The car runs great with the used AFM. I pried off the lid to the internals of the new/rebuilt one I just got and saw that the insides did not look as good as the repainted outside. A bit worn along the slider, but nothing broken. Can't tell anything about its settings just looking at it, but the idle screw under the rubber plug was turned way "up" in the hole compared to the one on my original unit. I wonder if a shop can set the settings on my new AFM without it being in the car, if I were to just bring it in...
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shawn62
- Posts: 23
- Joined: Sat Jul 26, 2008 8:38 am
I don't mean to highjack but some of these problems sound like what I am have trouble with on my 411. The car starts and runs fine for 5 mins then the idle slowly start to decline until it almost stalls, the engine will then rev back up and the whole thing starts over again. I can stop this from happening if I press on the gas pedal a little but the car runs like crap when I drive it. I have a new fuel reg and the fuel pressure gauge I used is showing 30 psi while it is running. The engine runs great until after 5 mins of running. I am not have any trouble with the fuel pump, it is working like it should.
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raykinsella
- Posts: 82
- Joined: Thu Sep 14, 2006 6:36 pm
your 411 has D-tronic fuel injection, so the Air Flow Meter problems I've been having won't apply to your car. I wonder if your - what's that thing way over on the left side? the pressure sensor? is worn and can't hold a vacuum? I have a '71 411 with d-tronic and have never had these symptoms, at least not yet.
I'm sure Ray will have some helpful ideas when he reads your post. Stay tuned!
I'm sure Ray will have some helpful ideas when he reads your post. Stay tuned!
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wildthings
- Posts: 1171
- Joined: Thu Jun 03, 2004 12:42 am
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raygreenwood
- Posts: 11906
- Joined: Wed Jan 22, 2003 12:01 am
Yes...Shawn, in general that symptom is a rich running symptom. It can be caused by small vacuum leaks, a leaking Diaphram on the MPS (same thing), fuel pressure issues, bad CHT, sloppy trigger points or even very sloppy high resistance connections to parts in the system.
The same rules apply for adjusting an MPS as they do for adjusting the AFM on L-jet. DO NOT adjust it.....until you are absolutely sure that all else is PERFECT...not just decent....not just "it looks okay"...not just "it was running ok with that part before". PERFECT!
If you have not replaced a part, hose, seal or connection....YOURSELF...within the last 1.5 years...then it is suspect in D-jet or L-jet.
Even if you bought a brand new fuel pump, injector or fuel pressure regulator....YESTERDAY....it must be checked. Fuel pressure should be measured at idle and under load. Injectors ...especially new ones....should be checked for spray pattern, flow and resistance.
If there is any thing off...or suspect...and you adjust the AFM or the MPS, when the offending part changes again (usually temp change)....or you find the offending part finally.....your AFM or MPS adjustment will have to be done over again. Adjusting an MPS properly is tedious and time consuming.
You could easily spend one whole afternoon checking what you should be checking in order to get set up to adjust the MPS or AFM.
Every hose new or in very good condition
Every hose, clamped with newly trimmed ends
Intake runners to head gaskets, check hot and cold. They notoriously leak.
Intake runner boots....and clamp them. They leak once teh engine is warm
TB o-ring
TB shaft seals
injector seals
Oil filler seal...another common leak.
Valve cover gaskets
PCV valve...get rid of it...its a defecetive design
PCV hoses to head
Vacuum modulator and hose on automatic
TB dash pot on automatic
Vacuum advance unit...commonly leaks
Adjust deceleration valve
Auxiliary air regulator....must close on time and not leak at all
TB spring must close all the way
Injectors as listed above
Throttle valve switch adjustment.....AND the correct adjustment is NOT in the book.
Valve adjustment. CRITICAL on D-jet
Timng adjustment CRITICAL
Fuel pressure....at idle...at open throttle....and leakdown
Check resistance of all inejction parts and sensors
Check resistance of trigger points....this is almost always bad.
If all of this is not DEAD ON...you have no business adjusting either the AFM or the MPS. It just shifts teh bad driving up and down the rpm and gear position range. You can piddle for years and not get it right unless you start with all else correct. Ray
The same rules apply for adjusting an MPS as they do for adjusting the AFM on L-jet. DO NOT adjust it.....until you are absolutely sure that all else is PERFECT...not just decent....not just "it looks okay"...not just "it was running ok with that part before". PERFECT!
If you have not replaced a part, hose, seal or connection....YOURSELF...within the last 1.5 years...then it is suspect in D-jet or L-jet.
Even if you bought a brand new fuel pump, injector or fuel pressure regulator....YESTERDAY....it must be checked. Fuel pressure should be measured at idle and under load. Injectors ...especially new ones....should be checked for spray pattern, flow and resistance.
If there is any thing off...or suspect...and you adjust the AFM or the MPS, when the offending part changes again (usually temp change)....or you find the offending part finally.....your AFM or MPS adjustment will have to be done over again. Adjusting an MPS properly is tedious and time consuming.
You could easily spend one whole afternoon checking what you should be checking in order to get set up to adjust the MPS or AFM.
Every hose new or in very good condition
Every hose, clamped with newly trimmed ends
Intake runners to head gaskets, check hot and cold. They notoriously leak.
Intake runner boots....and clamp them. They leak once teh engine is warm
TB o-ring
TB shaft seals
injector seals
Oil filler seal...another common leak.
Valve cover gaskets
PCV valve...get rid of it...its a defecetive design
PCV hoses to head
Vacuum modulator and hose on automatic
TB dash pot on automatic
Vacuum advance unit...commonly leaks
Adjust deceleration valve
Auxiliary air regulator....must close on time and not leak at all
TB spring must close all the way
Injectors as listed above
Throttle valve switch adjustment.....AND the correct adjustment is NOT in the book.
Valve adjustment. CRITICAL on D-jet
Timng adjustment CRITICAL
Fuel pressure....at idle...at open throttle....and leakdown
Check resistance of all inejction parts and sensors
Check resistance of trigger points....this is almost always bad.
If all of this is not DEAD ON...you have no business adjusting either the AFM or the MPS. It just shifts teh bad driving up and down the rpm and gear position range. You can piddle for years and not get it right unless you start with all else correct. Ray