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99 E320 P0300 etc codes (not MAF?)

6K views 9 replies 4 participants last post by  fourflattires 
#1 ·
I got all the typical misfire codes, P0300, P0304, 0305 etc. The drivability issue came out of nowhere. Super sluggish, turning the key off, then back on gets me up and running again (vs almost no power).

but.....

My new BOSCH MAF did not solve the problem. I am tossing the same codes back to the scanner, but this time am not getting the P0170 fuel trim (yet) where i did get that back in the begining.

Could it be fuel pressure? How to check?

Specifics: recent plug change 5k miles ago, 110k miles on motor, issue free.

Thanks,

Jeff
 
#2 ·
Post the codes

First,all of them so we can have a look see.Is it mult misfires0300 plus 04,05,06?that is the whole right side bank facing to the engine bay,if it was a filter or pump or pressure issue before the injectors it would affect all the cylinders.check your wires are all pushed tight to the plugs,check for leaks in vacuum lines,clean the injectors with some techron cleaner.Does it die out when running and restart only to have it repeat again?List the symptoms.Did you have just a p0170 code before or both p0170 and p0173? if only p0170 look for a leak in the intake system.
ohlord
"GOT CODES?"
p.s. did you do the plugs?really check that the boots are popped on firm,they sort of softly click on to the plug when on correctly ,you will feel it.
 
#3 ·
I concur with ohlord. Since you're in AZ given the age of your car you might also be looking at plug wires. Even aside from the climate if they weren't removed correctly to change the plugs that can damage them.

Re: reinstallation, I personally recommend using a little dielectric grease inside the cap, that cuts down on the possibility of corrosion/water issues and acts as a lubricant to help those boots pop back on more easily.

Also, if you did the plugs how sure are you that the coils were properly reinstalled and the wires correctly located?

Take care and enjoy the ride,
Greg
 
#4 ·
coil wires

Coil top wire front plug,bottom wire rear plug,all cylinders.check em
ohlord
"GOT CODES?"
 
#5 ·
Yeah, it will really screw thing up if the plug wires from a coil for a cylinder are reversed, since the plugs sometimes fires simultaneously, and sometimes sequentially.
 
#6 ·
Folks...sorry for the delay. I had been on vacation.

Recapping, codes were
P0300 random misfire
P0305 misfire #5
P0302 #2
P0304 #4
P0303 #3
P0306 #6
P0170 fuel trim

I replace the new maf with the old one....same performance. Misfires, poor idle, turn the engine off, restart, and she runs better for only a bit, then back to almost no power.

Still thinking it might be fuel pressure, I get a solid 55psi at the fuel rail schrader valve connection. I was suprised to see my R12 AC manifold gauge hook right up to that fitting and used the low side guage to read the psi (tip!).

When I blip the throttle i think I hear a vac leak from the right side, closer to the back of the manifold, but it is only temporary and I think this is just air flow noise. Spraying around, I dont delect any vac leaks.

re: plug wires. I just dont get the impression this is plug wire related. They had performed flawlessly for 5k miles since the tune up, but I did double check the plug wire routing and all is well.

CPS was replaced about 7k miles ago, due to a hot no-restart issue. The CPS totally cleared that up.

Thoughts? Could I have a new defective BOSCH maf right out of the box?

Thanks,

Jeff
 
#7 ·
Hi, Jeff.

Hope you had a nice vacation.

You mentioned fuel pressure, did you change the fuel filter though? There is a write up in the DIY thread, pretty easy job. Of course there is no code for the fuel filter.

I doubt you have a bad MAF out of the box, besides you're not getting both codes. Something is affecting both sides of the engine, though.

Take care and enjoy the ride,
Greg
 
#8 ·
okay

so the misfire is on both banks and is random.Vacuum leak,egr valve,fuel pressure.I'd start with the vac lines and also a good look over of the intake tubes you removed to replace the maf.A propane torch not lit and turned on to a low hiss and traced carefully over the tubes and vac lines will show you where the leak is,the engine will speed up at the point of the leak.If clear clean the egr tube with the old speedo cable threaded thru the tube exiting the egr and spun in a drill.Last the filter per gregs210
ohlord:bowdown:
"GOT CODES?"
 
#9 ·
Final update - FIXED

Well, its fixed. After trying to find a non-existent vacuum leak and double checking all prior work, I nursed it towards my local indy for diagnosis.

I knew I was in for an hour min diagnosis ($96/hr) but trust the shop as they are two doors down from my office. The call came in, diagnosis was both sides had bad cats. With the estimate being $1574 I choose to shop around. I purchased OEM cats for significantly less than list and installed at home.

Both cats came off in under an hour using jackstands and basic tools everyone has.

Fired it up, and no codes. The car is back to being a rocket ship. I would cut open and show everyone the clogged cats, but I am finding there is a market for used cats and will be selling them. Ironic, but true.

Thanks for the posts. Case closed.

Jeff
 
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