since ive got her running good ive developed a few misfires

p0301 is how it started so i replaced the upped and lower intake gaskets and the imt gaskets. i also moved all the coils from the rear bank to the front. now im getting p0301 and p0304 lol the brake booster line and the pvc hose from the air cleaner to the intake are good.any ideas on what else i could seal up. ive actually sold the car and need to fix these before the guy picks it up lol i can get fuel trims tomorrow. the car starts to miss at like 5k rpm then goes into limp mode! thanks guys!

 

Adam, because the misfire moved, I would question the coil that is on cylinder #4 right now. I would then access the plug for cylinder #1 and clean that. Because it was misfiring before, the plug may simply be fouled and that is what is causing the misfire. See what you have at that point and then go from there.

 

It's weird because I moved the packs straight across 1 to 2 and 3 to 4 etc I was expecting a p0301 I actually just checked the plugs in the back bank all where good and also no oil in the plug wells or on the plugs. I'm going to get a few coils and try that. Also is that vac hose on the back of the intake known to cause issues, mine seems kind of loose.

Thanks again

 

I would think if you would have a problem with the brake booster leaking you would be getting a lean code, Like P0171 or P0174 that would indicate a vacuum leak.

 

Replaced the 3 coils on the easy side today still getting a p0301 lol going to swap some around again such a pain in the butt to take the intake off. Hopefully this will cure the issue it's weird it on happens on hard acceleration like 5-6k. I also replaced maf and the sensor on top of the intake and the vacuum hose from the fuel rail to the back of the intake. Seems somewhat smoother now I guess the old coils are just shitting the bed.

 

Well thought I had it fixed. I cleaned and swapped injectors, I got a new coil I checked the wires coming off the coils and put a new spark plug in. It fixed the misfire for 1 day lol. Now p0301 is back. Throwing the car into limp mode when you hit about 5k rpm. I found a small vacuum leak on the plastic line going from the top of the tb to under neath the o2 sensor connectors.

Anyone have any ideas?

Thanks again guys.

 

So ive torn it apart again and pinned the coil harness got good results on everything. so i swapped plugs and coils from bank 1 to 2 lol again. i also pinned the injector harness from the main injector connector to the cylinder 1 injector also good continuity. i hooked up my injector tester to the cylinder 1 and watched the spray it also looked good. and ran a constant pulse for 5 mins and it did not stop i cant really see a problem with the injector. it ohmed 15ish so should be fine. im stumped on this. i guess tomorrow a compression test and leakdown test on cylinder one. maybe a weak spring ?? idk i would think if it was a valve or rings it would miss at all rpms not just around 5k. its so odd that it ran fine for a day then started up again.

also my freeze frame has weird readings i was watching the reader when it happend and the frp was 57ish and im pretty sure the ect was not in the 300s i recorded the live data when i was driving but it look weird now that i hooked it up to the computer. im not sure whats going on. im suppost to give the car back to this guy this week end i need help lol SOS if anyone one has any ideas id like to give them my phone number and talk directly it would be very appreciated and i could compensate them with some cash when i get paid. anyways i plan on hitting this hard again tomorrow ive got to get the issue figured out.

thanks in advance!

Adam

 

From a long time S TYPE contributor =
And since you mentioned a misfire, you have to listen to my canned speech on the subject. I'm waiting for a forum regular to turn this into a drinking game, where one must down a shot every time I get up on my soapbox:

If the computer has set a misfire code, please be aware "misfire" wasn't the best terminology that could have been used. Misfire sounds like an ignition problem, at least to me, meaning the fuel and compression were there, but for whatever reason, the required spark was missing or weak. This might lead an aspiring mechanic to troubleshoot the daylights out of a perfectly good ignition system. I do not care to discuss how I know this.

In OBD-speak, misfire simply means one or more cylinders is putting out low power compared to the others. Pretty much anything affecting the output of a cylinder can set a misfire code. It can be low compression. It can be a valve not opening fully. It could be a clogged fuel injector. And yes, it could be an ignition problem, too, but don't overlook the other possibilities, too. [/soapbox mode off]

Idk what to tell you, other than bad cylinder?

Causes =
Faulty spark plug 1
Clogged or faulty fuel injector 1
Faulty ignition coil 1
Fuel injector 1 harness is open or shorted
Fuel injector 1 circuit poor electrical connection
Ignition coil 1 harness is open or shorted
Ignition coil 1 circuit poor electrical connection
Insufficient cylinder 1 compression
Incorrect fuel pressure
Intake air leak

I did see one mention of a failing throttle position sensor causing this. I'm a bit suspect about that, but reported once.

 

I've looked at every thing that I know I'm just stumped about why it happens at 5k rpm only if it had bad rings or a burnt valve wouldnt it be a all the time condition? Also when I tore it apart and cleaned the injectors and a few other things it fixed it for a couple days then it came back. I've never heard of rings or a bad valve coming back to life like that..but I'm not a mechanic I'm just trying to do my best here.

 

FRP 8.5 psi looks odd.

Bear in mind it could even be a part-blocked cat.

 

Nice catch JagV8, yeah that fuel rail pressure looks way off, like WAY off. It couldn't be as simple as a clogged fuel filter?

And ECT that high will cook an X head very quickly, repeat very quickly. Hope that it's the sensor acting up or bad.

 

Ya something is wrong with my scanner because when I was driving I watched it and my frp was 55-60 and coolant never went past 200ish. I just changed fuel filters yesterday it was the original one, made no difference.

 

Intermittent fuel pressure sensor? Right by the temp sensor too btw.

 

here is the freeze frame and idle and 2500 rpm readings

 

What are all the other DTCs?