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#751570 - 07/26/05 10:09 PM Please help - Code 34
pesuazo68 Offline
Rookie

Registered: 01/26/04
Posts: 72
Loc: Raleigh, NC
Car 1987 MGM, 5.0 EFI, 88k miles.
Dreaded high idle showed up (some days idle is normal, which leads me to believe it is not a vacuum leak).
I did a search and found tons of good info. I decided to check the codes before attempting fiddling with TPS or ICV.
I get code 34, both HARD and MEMORY.
From sticky above it means something wrong with the EGR valve. From dalidesign code 34 is dependent on whether I have an EVP, EVR of PFE system. How do I know which one I have?, Is there something I could attempt before replacing the EGR? (like cleaning it?)
Where exactly is the EGR?
Any help is appreciated, I am expecting to fix this problem next weekend, as well as install my gauges (pics will follow).
Thanks in advance

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#751571 - 07/27/05 12:45 AM Re: Please help - Code 34
Bobert2647 Offline
Posting Addict

Registered: 09/16/04
Posts: 21189
Loc: Rochester Hills, Michigan
34) Insufficent EGR flow/ or EVP voltage above closed limit.

Either the valve is shot of the sensor on it is stuck or shot. It's about 90 bucks to replace both new if it comes to that.

It's right on the intake just before the throttle body facing towards the front of the engine bay. There is a green vacuum line going to it and a black round-ish electrical connector going into the bottom of it.

You can take it off it's only 2 nuts that hold it on. I'd get some Valvoline SynPower Air Intake and Throttle Body Cleaner (it's strong stuff) to clean out the 2 ports behind the valve. Using the cleaner on the valve itself I heard is not good for it.


Edited by Bobert2647 (07/27/05 12:54 AM)
_________________________

2007 Ford Crown Victoria P71 SAP

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#751572 - 07/27/05 01:13 AM Re: Please help - Code 34
Petely Offline
Poobah

Registered: 06/26/03
Posts: 5164
Loc: Chicago, IL
Code 34 is the EGR valve solenoid or the egr valve position sensor. The EGR valve solenoid (controls the amount of vacuum to the valve. fails the most becuase the rubber components rot with age. My 87 needed it replaced. Make sure the valve operates smoothly by using a screwdriver to push on the round metal bushing accessible thru the openings on the valve. Don't press on the diaphram itself.
_________________________
Peter
1987 Mercury Grand Marquis
*sold to some guy on cvn for $1
New Long List of Rules Compliant Sig

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#751573 - 07/27/05 01:53 AM Re: Please help - Code 34
BoxMan Offline
Grand Poobah

Registered: 01/21/02
Posts: 11514
Loc: Millville, PA
Sensor needs replaced probably.

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#751574 - 07/27/05 08:21 AM Re: Please help - Code 34
pesuazo68 Offline
Rookie

Registered: 01/26/04
Posts: 72
Loc: Raleigh, NC
What are your opinions on the relationship of this problem with the high - low idle?
Are they directly related?
Is there a way to test it while in vehicle? (or outside)


Edited by pesuazo68 (07/27/05 08:25 AM)

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#751575 - 07/27/05 09:21 AM Re: Please help - Code 34
Petely Offline
Poobah

Registered: 06/26/03
Posts: 5164
Loc: Chicago, IL
The EGR valve would cause a low idle and possibly stumbling if left open when idling. Thus under all conditions, the EGR valve should be CLOSED when idling. If it is fully closed then it should be idling fine if all other systems are fine even if the EGR position sensor failed or the EGR valve solenoid failed.

Idle speed is determined by a few conditions in a working car with no vac leaks (cold loop/warm loop, TPS, IAC, MAP). First off the car has to know whether to be in cold loop or warm loop and this is based on coolant temperature. During cold loop the IAC opens up more allowing a little more air and it also dumps in more fuel than warm loop. Once it enters warm loop the IAC cuts down the airflow and fuel mixture is leaned a bit. The IAC, TPS and MAP contribute to the idle at all times. The IAC is the motor that allows a certian volume of air to pass based on the info from the computer. This often gets clogged and jammed with carbon and debris. The TPS informs the computer of the current position of the throttle and if this is not returning the proper info it can mess a lot of things up. Generally, an excessive idle is noticed. The MAP sensor helps determine the amount of air entering the engine. Overtime these units don't respond as well and experience what they call drift (their output is a frequency) Even a 3Hz drift is enough to impact performance.

_________________________
Peter
1987 Mercury Grand Marquis
*sold to some guy on cvn for $1
New Long List of Rules Compliant Sig

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#751576 - 07/27/05 11:15 AM Re: Please help - Code 34
pesuazo68 Offline
Rookie

Registered: 01/26/04
Posts: 72
Loc: Raleigh, NC
Thanks to all for the responses.

In addition to removing and cleaning the EGR, I will remove and clean the IAC (I recently cleaned the throttle body to a shine, also the little screen-metal mesh under the PCV valve, PCV valve is only 2 years - 20K miles old). I will also check the TPS voltage.
Where is the MAF?, and how do I test it?
I have an oscilloscope, DMM and other electrical/electronic testing equipment.
I have had several instances (within a week) were the car stalls at idle. Most of the time it happens when I am backing up from a parking space, and have the wheel turned all the way in either direction.
Would a dirty IAC (not closing or opening correctly) would also throw a code?
I ask because the car did not have any other codes.

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#751577 - 07/27/05 05:38 PM Re: Please help - Code 34 - UPDATE
pesuazo68 Offline
Rookie

Registered: 01/26/04
Posts: 72
Loc: Raleigh, NC
I just got home. The moment I stopped and placed the transmission in P the idle went up high, and stuck there.
While the engine was running I removed the electrical connection to the IAC and the engine went down immediately (perhaps lower than normal for what I could observe). The moment I plugged it in the idle shot high again (plugged and unplugged a couple of times with same results).
Even though I have a code 34 (EGR), I certainly will take a very close look at the IAC on Saturday (clean it well, I may even do it this evening but is hot as hell here in Raleigh. I rather stay indoors)

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#751578 - 07/27/05 05:44 PM Re: Please help - Code 34
Petely Offline
Poobah

Registered: 06/26/03
Posts: 5164
Loc: Chicago, IL
Generally the IAC malfuncationing will not show any codes since it is just a motor. People don't have very good luck cleaning them. I doubt you have a MAF sensor. I think you are referring the MAP sensor which is located on the top of the firewall on the passenger side of the car. There is a rubber vacuum hose and a connector with three wires on it. If you want to test it, the map should output 159Hz at sea level. Then you would subtract 3Hz for every 1000ft rise in elevation. A 10Hz drift is a pretty significant drift and should be replaced becuase its beyond the capability of the o2 sensor to compensate.
_________________________
Peter
1987 Mercury Grand Marquis
*sold to some guy on cvn for $1
New Long List of Rules Compliant Sig

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#751579 - 07/27/05 06:10 PM Re: Please help - Code 34
Petely Offline
Poobah

Registered: 06/26/03
Posts: 5164
Loc: Chicago, IL
The engine should die when you unplug the IAC unless you have a vac leak or the IAC is failed.
_________________________
Peter
1987 Mercury Grand Marquis
*sold to some guy on cvn for $1
New Long List of Rules Compliant Sig

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#751580 - 07/28/05 08:32 AM Re: Please help - Code 34
pesuazo68 Offline
Rookie

Registered: 01/26/04
Posts: 72
Loc: Raleigh, NC
Although the engine did not die, it was idling VERY low when IAC was unplugged (almost stall).
I checked the TPS voltage. Approximately 1 volt (0.98-0.99)
Is that good?

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#751581 - 07/28/05 02:31 PM Re: Please help - Code 34
AOD Offline

Grand Poobah

Registered: 12/06/00
Posts: 11487
Loc: Asheville, North Carolina
Your car should not be running with the IAC unplugged. That means yours is stuck. Hence the surging idle. Replace the sensor and be merry.

As for the TPS voltage, you are spot on.

~Adam
_________________________

'85 2-Door Crown Victoria - Faster than the Sig Police!
302 HO, -0.022" E7 Heads, Weiand Intake, Edelbrock 1406 Carb, Mechanical Fuel Pump, HEI Distributor, 180* T-stat, Shift Kit, HO Governor, Lokar Cables, B&M Torq Master Converter, FRPP Trans Cooler, Mustang Headers, 2.25" Dual Exhaust, Flowtech H-pipe, Hooker AeroChamber Mufflers, 2.5" Side-Exit Exhaust, Police Shocks, Cut PI Front Springs in the Rear, PI Rear Sway Bar, 17" Sport Wheels, 245/50/Z17 Tires, 4.10 Rear End Gears, Trac Lok Diff
'05 Crown Victoria LX Sport '02 Jeep Liberty '95 Mazda Miata '82 Honda MB5 Motorcycle

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#751582 - 07/29/05 03:14 AM Re: Please help - Code 34
BoxMan Offline
Grand Poobah

Registered: 01/21/02
Posts: 11514
Loc: Millville, PA
Yes, replace that IAC.

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#751583 - 07/29/05 01:07 PM Re: Please help - Code 34
pesuazo68 Offline
Rookie

Registered: 01/26/04
Posts: 72
Loc: Raleigh, NC
Quote:

Yes, replace that IAC.



That will be done after the Code 34 is taken care of.

Thanks to all for the replies.

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#751584 - 07/30/05 05:59 PM Re: Please help - Code 34
pesuazo68 Offline
Rookie

Registered: 01/26/04
Posts: 72
Loc: Raleigh, NC
Quick Update:
I remove the EGR valve and the IAC today.
The EGR's plunger was somewhat dirty with carbon, it would slide back and forth, but I could tell the roughness in the travel (and the possibility of not closing completely). The red diaphragm looked pretty good. I carefully cleaned and lubricated the shaft (and plunger) until the travel back and forth was nice and smooth.
The orifices in the throttle body looked pretty clean.

The IAC was very dirty, the shaft was covered with about 1/8" of hardened carbon. The round "thingy" between the 2 shafts was also very dirty. I cleaned it very well, making sure I would rotate the inner shaft to get it all around. By the time I was done the shaft was reddish (original color?), instead of coal black.

I put everything back together, the car idles like a dream.
I will wait at least one week before I can decide whether the problem is solved.
Tomorrow I will start working on the gauges. Is there an easy way to get to the engine compartment from the passenger side?.
I am installing mechanical gauges (with angled rings) in front of the passenger seat, but I am concerned the water temperature and oil pressure piping will not reach. I may be able to extend the oil pressure pipe, but the temperature "wire element" is not "extendable".

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