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Discussion Starter · #1 ·
I have been searching and searching- haven't found an answer and I need help!
I bought this car used and not running so I took my chances. I am a good mechanic but this thing has got me stumped!
Symptoms:
Missing at idle- running rich and very ruff at idle.DPFE hoses were blown off and egr pipe was broken. Replaced plugs, rear cat,DPFE and egr valve. There is enough pressure coming thru the EGR pipe to slightly open the egr valve with the hose unplugged. (the pipe going into intake manifold gets hot!) If you blow into top of egr valve it closes and runs a little better.
I disconnected the exhaust to eliminate back pressure- it still seems to have too much pressure coming out of rear cat that is new.
Did compression test- all seems good there.

Trouble codes P2195,P2196,P2198

Freeze frame:

STFTRM1 33.5%
LTFTRM1 0
STFTRM 2 33.5%
LTFTRM2 0

CMDEQ .999
O2S11 .105V
STFTRM11 34.3%
O2S12 .010v
STFTRM12 99% (???)
O2S21 .935v
STFTRM21 34.3%
O2S22 .140V
STFTRM22 99.2%

Sorry for length of post but I am stumped and confused!
Any clues???
 

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This might be old school but put a vacuum gauge on the engine and see what happens for readings.

EGR system - no egr valve should be open at idle, verify this is closed and gradually opens off idle. Verify the routing of the tubing to and from the EGR valve is correct as well. Actually, I would get a diagram of the EGR system and double check all the hoses are correctly connected/routed. If the EGR valve hangs open at idle it will run rough. Verify you have no vacuum leaks using the vacuum gauge.

If the car is running rich the only things that I know that could cause this is a bad MAF sensor and/or bad O2 sensors. Of course I'm assuming the PCM has no defects either.

Keep in mind if you get at trouble code that doesn't mean the component is bad. It may also mean there is something wrong with the system. For example, with the EGR system what other components must be in place for the EGR valve to operate correctly? You have to look at things from a system perspective.

How many miles on the engine?
Monsoon
 

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Discussion Starter · #4 ·
Miles unknown..

Thanks for reply!
Car has 120 k on it but maybe a junkyard motor. Its marked "no oil" in yellow ink pen on oil pan.
The pressure coming out of the EGR pipe is enough to open the EGR valve with NO vacuum hose attached!
Thinking of pulling the injectors and having them tested- running out of thoughts...
 

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Thanks for reply!
Car has 120 k on it but maybe a junkyard motor. Its marked "no oil" in yellow ink pen on oil pan.
The pressure coming out of the EGR pipe is enough to open the EGR valve with NO vacuum hose attached!
Thinking of pulling the injectors and having them tested- running out of thoughts...
I would solve the EGR problem 1st. This could be the root cause of your problem. May be you've got a bad EGR valve? Remove the EGR valve and block it off with something (sheetmetal) and see if the idle condition improves. Make sure you block the vacuum side of the port inside the casting.

Plug wires, spark plugs and fuel filter. If these have over 100K miles get new ones.

Monsoon
 

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Since your exhaust gas is rich, its recirculation through EGR may beat the purpose of EGR. It can make rich running worse.

Unburnt fuel will increase exhaust back pressure since hydrocarbon is oxidized to CO2 and H2O in cat converter.

The root cause seems to be incomplete burning and sending fuel to cat converter. Since you have new plugs, what about wires and coils?

I am not a mechanic, and these are my inexperienced guesses, but not totally unreasonable

EDIT

Monsoon,
He has new EGR valve. Apparently, excessive backpressure is lifting up the diaphragm. OP says so.

OP,
I would guess failing injectors will flow less fuel. If so, they cannot cause rich burning.
Excessive fuel pressure may.
 

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If injectors are stuck open and excessive fuel flows constantly, will they cause high LTFTRM or high STFTRM? More likely LTFTRM.

I wonder if simultaneous rich and lean codes suggest an intermittent problem. I am sure 'tech advisors' can lead you in the right direction.
 

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Discussion Starter · #9 ·
Oredered new oxy sensors and pulled out the injectors for testing.
Re-did compression test- highest is 205 lowest 185.
Still a mystery,....
 

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Discussion Starter · #13 ·
FOUND IT FOUND IT!!!
The S pipe for the cats- where the down pipe for rear cat mounts- welded nicely but- THEY DIDNT CUT THE HOLE!!!
So essentially the rear head exhaust was dead ended against the bottom S pipe!
What a Bizarre problem!
 
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