Random Multiple Misfire and More.

[BAStumm]

History: Had this vehicle for a little over a year. Last spring had the intake manifold gasket replaced due to a coolant leak. Vehicle had some missing problems then also. At that time only p0300 showed. Currently it shows these codes:

P0133, P0300, P0303, P1151

Info obtained via a mac tools et50 scanner. It also allowed a freeze frame while driving which provided some odd data (or I think it is):

Fuel Sys Stat B1=0 B2=0
Load: 65.09%
Coolant Temp: 88 C
S.T. Fuel Trim B1 0.77% B2 0.77%
L.T. Fuel Trim B1 -1.57% B2 -1.57% <------ ???
Engine 1888 RPM
Veh Speed: 87 km/h

I've also seen P0304 a few weeks ago but cyl 4 misfire hasn't returned in 3 weeks at least. No codes seen for cylinders other than 3 and occasionally 4. Arent these on seperate sides of the motor thus controls by different O2 Sensors? Odd...

P1151 is lack of HO2S-21 switch. indicates lean.
P0133 is O2 slow response bank 1 sensor 1

Is this the symptom of some other problem or is 02 and possibly coil pack the quick and easy fix? Plugs and wires are new as of May or so. Dirty MAF Sensor?

I have to go through emissions before New Years and I procrastinated on this... Any ideas?

 

[manaen]

have you checked the fuel pressure and replaced the fuel filter lately?

When does the vehicle miss? (under load or idle)

have you run a vacuum test on the engine to see if it is within spec's?

 

[BAStumm]

Cleared the codes this morning using the scan tool. p0303 returned both while idle and also while driving (clearing codes several times along my 20 mile commute to work). p0300 has not returned yet today. p1151 comes back almost immediate after clearing codes. p0133 comes back sometimes and sometimes not in the 3-5 mins between clearing/reading codes.

Fuel pump was replaced a year before I obtained the car (past owner is a friend). Have not checked the fuel filter, is there an additional fuel filter on these rigs seperate from the one in the tank with the pump? Have not run a vacuum test, how would I perform one? I do have a fuel pressure gauge and will test that tonight perhaps. But the p1151/p0133 combo really seems to be pointing to a O2 sensor (bank 1 sensor 1). But the addition of the Cyl 3 misfire and random multiple misfire codes has me wondering if there is a different or additional problem.

Thanks in advance for any help/ideas...

 

[btexpress]

I may have missed it somewhere, but the year and engine would help in assisting you in diagnosis.

 

[BAStumm]

MyBad! 1996 Explorer XLT, 4.0L, Auto, 4x4 Control Trac.

 

[btexpress]

I assume this engine is the OHV, since you mentioned coolant leak from the gasket.

Are you noticing any misfires while driving, that you can feel? Or is it so slight it just sets codes? Hopefully you didn't use Bosch plugs, that alone can be a problem.

The freeze frame data you show doesn't indicate any serious problems with fuel trim, so I doubt it is an oxygen sensor issue. Any kind of misfire can skew the sensor readings lean. However, slow switching CAN be the sensor, but I would like to see the misfire problem fixed first.

I will look into tsbs and see if there is anything about a PCM update, some vehicles can get this fixed by reprogramming, if there is not an obvious misfire.

 

[btexpress]

Excuse me, I had a senior moment......the SOHC engine did not come out until 1997!

Provided you have no misfire SYMPTOMS to go along with the code. there were two TSBs early on that might apply, #97-8-6 regarding misfire codes and reprogramming; and #97-15-22 regarding the Po133, P1151, also reprogramming. These are 10 year old bulletins, so they may not apply, especially if you have symptoms of misfire.

Did these codes show up after the intake work? If so it is possible the rear of the intake did not seal properly and is allowing a small amount of umetered air into cylinders #3&4 causing the misfire codes.

At this point, it depends on if you are noticing an actual misfire or not as to where yoiu go next. The TSBs I mentioned concerned programming glitches, like the program was set to sensitive and is picking up false interpretations of the data. Since these are 10 years old, they have been done at some point already. Again, it depends on your symptoms.

 

[BAStumm]

Not sure what you consider noticeable but I believe I can "feel" the missing. At a stop light the vehicle shudders slightly and while driving it sometimes has a very slight "buck"
to it. Normally I do my own work on cars but the intake manifold gasket was done by a shop. I was in an (on the job) accident that left me unable to perform car repairs for a while so I had to hire the work out. Prior to the work I had only a few misfire codes, immediately after the work I had some O2 related codes getting set. The shop blew it off as coolant on the sensors as coolant was also leaking into one (or more) of the cylinders. Perhaps that has left a coating on the O2's that skews the readings. I dont know but find it odd that I didn't have O2 codes until I picked the car up from the shop.

 

[BAStumm]

wait a sec... I thought cyl 3 was at rear of engine and cyl 4 was at front of engine? 1-2-3 down one side of engine and 4-5-6 down the other side.

 

[btexpress]

wait a sec... I thought cyl 3 was at rear of engine and cyl 4 was at front of engine? 1-2-3 down one side of engine and 4-5-6 down the other side.

Duh, another senior moment, sorry about that ,you are correct about the cylinder placement. I didn't used to make that mistake when I only worked on Fords!

We have seen a good number of coil problems on these engines. But most of the time coil failures will create a definite misfire.

 

[BAStumm]

My gut tells me to replace the 02 (bank 1 sensor 1) and the coil pack BUT...

1151 code tells me about an O2 problem on bank 2 AND a coil pack is an all in one unit for about $180 and I figure its another $70 for an O2 Sensor. I'd hate to drop 250 and still have these codes set. In reality all I want to do is get the thing through emissions and here in Washington state if no codes are set then you pass. The car has 215k miles on it and emissions are only done every other year. I dont plan to have the car in 2 more years from now. After work I'm going to try to clear the codes in the parking lot of the testing place and cross my fingers that I can pass emissions... *grin*. But if that dont work I'll be opening the wallet up I'm sure. Just hoping to find the correct fix (hopefully for cheap) the first time.

as for noticeable miss... I feel its noticeable but it is definately not a backfire. It's a mild stumble at idle that makes the rig shake slightly at a stop sign. Its not constant either. Couple stumbles every few minutes.

 

[btexpress]

At this point I think your best bet is the coil, forget the sensor until you fix the miss

 

[ThePhoenix]

i would check the fuel filter first as its a cheap fix/chaNGE....then check PCV and egr stuff...

 

[BAStumm]

Failed emissions. Forgot about the readiness test and since I cleared codes in parking lot that failed. They reverted to old style test with wand in the tail pipe. Failed that too based on the HC level being to high, 265ppm with 220 or less as pass.

Remembered tonight that when I had the intake gaskets done that mechanic has an online service history. Turns out the car was throwing codes 303 and 153 back then. The 153, O2 code went away and never came back, however it still throws 303. And to top it off the 304 code came back. Immediately after the emissions test I checked codes and it had 300, 303 and 304 but no O2 related codes. So we'll be grabbing a coil pack in the morning I think. Informed my sons that one gets O2 sensors for christmas and the other gets a coil pack... Figured I'd let them choose. LOL.

 

[manaen]

you can test the resistance on the coil pack before you just throw another one in there. Also don't make the mistake of throwing o2 sensors at the problem, they are rarely the cause. Have you checked for vacuum leaks? that may be suspect since someone just worked on you intake gasket. There could be a vacuum hose split or hanging loose somewhere. check fuel pressure

Test the sensors before you replace them, with a multimeter you can test 98% of the sensors and diagnose if they are bad before you just swap parts.


How are the plugs looking, are they all burning properly?

All the wires are routed properly and not touching each other? or rubbing through on the headers or block?

clean the maf?

The fuel filter is mounted to the driver side fram rail right below the driver door, on the inside of the frame rail, so you need to slide under the vehicle to see it. You will need a fuel line disconnect tool to remove the spring clips on the lines.

Oh and did I mention testing your fuel pressure?

 

[ThePhoenix]

i thought the fuel filter was by the tank?

 

[manaen]

i thought the fuel filter was by the tank?

there is a screen on the intake for the fuel pump, however the actual filter is located on the driver side frame rail. It is a metal canaster style filter.

 

[ThePhoenix]

is it different per year?
because I was going off of this thread....for the 04

http://www.explorerforum.com/forums/showthread.php?t=198626&highlight=fuel+filter

yet you have an 01 like I do....maybe thats why I couldnt find it

 

[manaen]

is it different per year?
because I was going off of this thread....for the 04

http://www.explorerforum.com/forums/showthread.php?t=198626&highlight=fuel+filter

yet you have an 01 like I do....maybe thats why I couldnt find it

exactly, all gen1's and gen2's have the filter inside the driver side frame rail

 

[BAStumm]

Installed a new coil pack today and after approx 5-10 mins of idling followed by a 12 mile drive I have yet to see the misfire codes (300, 303, 304) but codes 1151 and 0133 both returned during that drive. Battery was disconnected during the coil change so codes should have been cleared following the coil swap. The confusing part here is that 1151 and 0133 refer to separate banks or at least the info on code descriptions that I have seen seem to indicate bank 1 sensor 1 for the p0133 code and bank 2 sensor 1 for code p1151. Is that correct? Any ideas what might cause this?

MAF Sensor? Intake Leak? Vacuum leak? Could this actually be related to 02 sensors being the problem? Anyone have any insight they could share as to what exactly p1151 means as the info I've found seems vague.