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Discussion Starter · #1 ·
I need more help guys. I have a 1994 Ford Mustang GT, w/ HO 5.0l engine. The engine was recently replaced with the ford racing engine, GT-40 aluminum SVO "X" heads, X-303 cam, Cold air intake. Ran my engine codes today, came back w/ lean condition on right and left sides, and the EGR vavle postioning sensor having to much voltage in "closed" position...
My problems- Car has a bad miss at idle, and cruising speeds. Not at all noticable at WOT under load or not. Starts to "jerk" badly, and have some "tapping" or "chatter" in valves. HEAVY fuel smell under hood & exhaust.

Questions-1) Does the code for the EGR position voltage (code 334) mean that I need to replace the postioning sensor itself, or the EGR valve itself, maybe both?

2) Could this be the cause of the "lean codition" in both side banks?
3) Could this also be the cause of the terrible "miss" the car is having?

Engine has 8,000 miles on it since installed.. All stock ignition... Plugs gapped at .045.. autolite plug 3924 double platinum...

Thanks in advance for taking the time to help me, or the time to read!!
 

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Lean code for both banks is most likely a vacuum leak or a defective MAF sensor. You are smelling fuel because it thinks it is lean and is adding fuel to try to compensate.

What do the fuel trims look like
 

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Discussion Starter · #3 ·
This is the OBD I system ( which I am sure you know), I did the KOEO self diagnosis test, and the KOER test. Is there a way I can check the trims without a computer?
However, visually out of the tailpipe I am not seeing any "rich" smoke, and upon inspecting the spark plugs ( only looked at plugs 1 & 5) they're showing a wee bit of a lean condition also.
i have not lost any noticable power at WOT under a load at all, which is really confusing me? Thanks for the reply Chet
 

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I need more help guys. I have a 1994 Ford Mustang GT, w/ HO 5.0l engine. The engine was recently replaced with the ford racing engine, GT-40 aluminum SVO "X" heads, X-303 cam, Cold air intake. Ran my engine codes today, came back w/ lean condition on right and left sides, and the EGR vavle postioning sensor having to much voltage in "closed" position...
My problems- Car has a bad miss at idle, and cruising speeds. Not at all noticable at WOT under load or not. Starts to "jerk" badly, and have some "tapping" or "chatter" in valves. HEAVY fuel smell under hood & exhaust.

Questions-1) Does the code for the EGR position voltage (code 334) mean that I need to replace the postioning sensor itself, or the EGR valve itself, maybe both?

2) Could this be the cause of the "lean codition" in both side banks?
3) Could this also be the cause of the terrible "miss" the car is having?

Engine has 8,000 miles on it since installed.. All stock ignition... Plugs gapped at .045.. autolite plug 3924 double platinum...

Thanks in advance for taking the time to help me, or the time to read!!
If the EGR is closed when it should be open the mixture will be lean (on both banks)as now the missing exhaust gasses are replaced with atmospheric air. It would run with the correct mixture at WOT because the EGR is closed at that point and the computer knows that so it corrects the mixture.

Bogie
 

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Discussion Starter · #5 ·
If the EGR is closed when it should be open the mixture will be lean (on both banks)as now the missing exhaust gasses are replaced with atmospheric air. It would run with the correct mixture at WOT because the EGR is closed at that point and the computer knows that so it corrects the mixture.

Bogie
Thanks! That makes a lot of sense put that way! So with the egr positioning sensor showing 'high voltage' at closed postion... Would that mean that I should replace the EGR valve itself? or the EGR positioning sensor? Or both?

Both are quite reasonable priced, EGR valve at $79.99 and the EPS, @ $29.00..Just hate to just throw parts at it and never pin point the problem:confused:
 

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Thanks! That makes a lot of sense put that way! So with the egr positioning sensor showing 'high voltage' at closed postion... Would that mean that I should replace the EGR valve itself? or the EGR positioning sensor? Or both?

Both are quite reasonable priced, EGR valve at $79.99 and the EPS, @ $29.00..Just hate to just throw parts at it and never pin point the problem:confused:
Without detail testing it would be hard to tell whether it's the valve or the sensor, but odds would say it's more likely to be the valve as it takes a beating dealing with hot, corrosive gasses and carbon build ups.

Bogie
 

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Discussion Starter · #7 ·
Without detail testing it would be hard to tell whether it's the valve or the sensor, but odds would say it's more likely to be the valve as it takes a beating dealing with hot, corrosive gasses and carbon build ups.

Bogie
Thanks for all of the help guys. Will try to install both tomorrow. Just purchased the sensor, vavle is on order, will be in tomorrow afternoon.

Will keep you posted on progress after the install, and code clear.
Thanks again!
 

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Discussion Starter · #8 ·
THIS IS KILLING ME!!!

Okay so I have changed EVERYTHING that I can think of here! And I am still having this problem, and the same exact codes are popping up!

New parts installed thus far..(no parts are reman.)
~Distributor [gunna change pip, but noticed bearing wear in dizzy, timing set at 12 advance]
~Coil
~EGR valve
~EGR valve postion sensor
~EGR vacuum solenoid [the vacuum "switch" that controls open/close on EGR valve
~plugs [gapped at .045] double platnium autolites
~plug wires
~dizzy cap & rotor button
~new upper intake gasket [installed to check vacuum lines visually instead of by inspection camera that are under the intake]

Parts that I have inspected/cleaned thus far..
-Cleaned MAF sensor [noticed during inpection that both coil wires are intake]
-Cleaned vitually new IAC sensor
-Replaced ALL vacuum lines that are under hood, and inside pass. side between firewall and fender.
-throttle body cleaned and inspected

Plus much more that isnt coming to mind at the moment, I am at a total loss guys. I have just been throwing parts at it until my savings acct. is slowing leaving me lol.

Thanks for any help you have to offer, if you guys have ANY ideas that may help or even something else i can check i will appreciiate it.
 

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You need a scan tool with live data to see what is going on.
its OBD1 so if you can find someone with an old Snap-On brick it would be perfect for what you need
Some things I would look at
MAF rate at idle (if it is a MAF engine
MAP readings
O2 readings
ECT readings
Fuel trims
Vacuum reading
ETC

Without this information you are just throwing parts at it and that gets expensive and almost never works.
Also is it pinging, a lack of EGR will almost always lead to pinging
 

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Discussion Starter · #10 ·
Thanks Chet. I have tried to find the tool through friends with no luck. Would one of the 'actron' handheld devices from Autozone or another local parts store do these things for me? I have read the packages, and of course asked the personnel for help, yet they cannot provide this info either. The system I am talking about is kind-of reasonable at about $200 bucks. I do not plan on selling this vehicle, and i also have other projects that I could "hopefully" use this tool on, so I wouldn't mind making the purchase if it is helpful:spank:
 

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How old are the O2 sensors?

Egr valves, TPS sensor, O2 sensors are hard wearing parts and usually the first to go...add a weak fuel pump (they don't last forever) and it can be a pain to diagnose.

I have an Actron scan tool left over from my old 1994 SHO with Ford cartridge sitting collecting dust, send me a PM and we can work something out if you want it.
 

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Discussion Starter · #12 ·
Thanks Chuck for the reply, I sent you a PM. Sorry for the delay as college has had me busy.

Update: I am still having this problem and have perfored numoerous test.
~TPS voltage showed perfect at base and thru out WOT range.
~O2 sensors have not yet been changed by me so I do not know if they have ever been replaced.
~Today I checked my vacuum again, and my vacuum will not hold steady on my gage, Jumps between 10 -17 at idle. Is this normal? I have looked for vacuum leaks, changed hoses, and replaced the ones i have found to be damaged.
Fuel pressure regulator holds steady at 32psi at idle with vacuum on, 40 psi with vacuum off.
~Checked my plugs again and still looking as if a lean condition exsist.
~ Have not aquired a scan tool yet to look at live data, everyone I know only has the OBD II scanner.

What is the plug under my dash that looks like the OBDII plug? I tried a normal OBDII scaanner and it would not connect to computer.:smash:
 
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