97 XP 4.0 w/pushrod engine 185k, runs rough, poor mileage, MIL on, codes P1151 manufacrer contrl fuel air metering & P0153 O2 slow response bank 2 sensor 1. Already replaced plugs, wires, fuel & air filters, all O2 sensors (bank1 sensor1 twice), intake & valve cover gaskets, and just today the MAF. Cleared codes with scan tool, unhooked the battery while I ate dinner, about an hour, to clear data tables. Hooked battery back up, let it run for 10 minutes and went for a test drive with the ODBII scanner hooked up. Within 5 miles I got P1151 again! Don't have the P0153 yet but I bet I will tomorrow. Can't find vac leaks. Checked intake bolts for tightness. What am I missing? Is P1151 referencing the MAF or does something else "help" make that code? Thanks in advance, Vic

 

Vic, those codes sure do point to a vacuum leak somewhere. Maybe a leak coming from the brake booster?

 

Thanks for the quick reply loneranger, I checked the vac line to the booster and sprayed wd40 around the rubber seal to the canister and there was no difference in engine rpm or idle. I also sprayed wd40 on just about every spot I could think of that would have a vac leak due to a crack in the line or bad gasket seal but to no avail. Do the booster canisters spring leaks? Is there a particular place I should look re the booster?I'm gonna hate to do it but I may have to retrace my steps from when I replaced the intake gaskets to make sure I'm not missing a cracked vac line that runs around the intake. Take all the stuff off and really inspect inside the looms. BTW, what exactly does the P1151 mean? Tnx, Vic

 

Vic, the P1151 is "Lack of upstream heated O2 sensor switch, sensor indicates lean (Bank #2). Since both the P0153 and P1151 relate to the same O2 sensor, my first guess is that the sensor is bad. BUT, that dosen't explain the rough running and poor mpg, and besides you've already replaced it....?

Bank 2 is the driver's side, so I'd focus on that side.

Sometimes a bad brake booster will make a 'hissing' sound when the brake pedal is depressed. You can hear it from under the dash.

When you get a lean code on only one bank, it's almost always a vacuum leak somewhere on that side. Maybe one of the gaskets moved when you replaced the manifold, or a bad booster......???
Good luck
LR

 

Thanks, LR. I did get the P0153 code the next morning and after work I replaced the booster vac hose, it was chafed. I still had both P0153 and P1151 last night. Just for kicks I plugged the scanner in after work this evening and now I only have P1151. Dumb luck I guess. I'm resigned to the fact that I'm gonna have to remove and reinstall the upper intake to check for a gasket issue. Could a bad head gasket pop these codes? I replaced the intake gaskets because I was losing coolant thru the exhaust (coolant smell in exhaust and steam) and read that the intake gaskets might be the culprit. I assume it was coolant by the smell but I guess it could be from the wrong fuel mixture too, huh? After I changed the gaskets I stopped getting an O2 sensor code for the other side, Bank 1 sensor 1 so I thought I had it licked. Guess not.
Thanks again, Vic

 

This sounds like a tough one, Vic. The coolant in the exhaust might affect the O2 sensor, but the rough running shows that something is still not right. If it's still showing a white smoke exhaust, I'd suspect a blown head gasket. Sorry to say.....

 

Dude. Pull your plugs and check out what is really going on inside your cylinder heads. The PCM does it's best to tell you but it is a stupid computer. OK you changed both O2 sensors. Doesn't mean they were both "good" sensors. I'm not too familiar with your code or the interpretation. But if it truely means that it is not switching, and that's all it mean, it could be either rich or lean. I have a OBD-I and got the same code description but it did say lean. My plugs were black with soot - rich. The sensor was bad and telling the PCM the wrong thing (lean) and the PCM reacted by richening up the left bank. Give it a shot. Like CSI (crime sceen investigation) get the facts.

 

LR, I've been trying to avoid the head gasket issue by eliminating the less $$ stuff first but it was one of the 1st things I thought of when I saw the steam and got the O2 codes. That's why I did the intake gaskets.
Jharger, I've changed the plugs and pulled a few since to see what they look like. They look okay, light tan, don't smell funny, no carbon, but not "steam-cleaned" either.

I will redo the intake and look at the gaskets and the vac lines carefully. If I don't find anything I'll move towards the heads/gaskets. I'm hoping for a vac line or intake gasket.
Thanks guys! Vic

 

All right I double checked the code, too tired to look it up last night. O2 switch #2 not switching and lean. Not sure if you have a left/right O2 set up or a before/after CAT O2 set up. If it is left/right then you can concentrate on just one side.

Now are you still getting steam out the back or did that go away with the intake gasket change?

If no steam now, I would think 1) you have a leak and get un-metered air into the system driving a true lean condition. (Vacuum leak did this to me a couple years ago.) 2) The MAF meter is off. Air intake or coolant temp reading too high. These would all affect both left and right banks. Or, 3) if just one side is being affected, and you have a right/left bank O2 system, then you have a bad O2 sensor. (I know you just changed them.) Reason is simple - nothing else in the controls system affects just one side of the engine. Another way to point to the O2 is it running in open loop when fully warmed up? O2 is the main reason for open loop operation.

Now if you are getting steam and loosing coolant out of the rdiator it is oviously going through the engine. Either the intake gasket change didn't seal right or it is going through somewhere else. If it is the intake, then I have a great article I found on sealing this baby up. It goes into great detail about where and how much RTV to use. It recommends Ford OEM gaskets over Fel Pro due to rubberized end seals over cork. Send me a private message with your email address and I'll send you the article.

So then if this isn't it, you are on the right track. Next to check is head gasket. But then which side? Spark plugs and a R/L O2 system will tell you which side.

I can think of 2 worse scenarios. First is a cracked head. Apparently not an uncommong thing for these motors. This means inspection and possible magnifluxing. Next is a cracked block. I had this happen to my old 302. Excessive detonation broke all my rings and piston skirts off. It finally scored one cylinder sidewall all the way through to the water jacket. Boy that was fun driving down the street. White smoke everywhere. I went through all these steps and couldn't find the leak until I used a flashlight and inspection mirror to see the crack inside the cylinder.

I'm kind of leaning toward getting a new O2 sensor. If it is still good, you have a spare. Or, if it is a R/L system, switch the sensors from side to side and see if the code follows.

Let us know what you find out as this is a tricky one.

 

Forget the email. I found the link to the intake manifold document. Also includes a Ford TSB.

http://rockledge.home.comcast.net/Ra...eplacement.pdf

Also check the postings on this in the 4.0 Engine forum.

 

Jharger, the intake article is the one I had when I did the job. It's very good. I do have r/l O2 sensors before the cat as well as one after, 3 total. Yeah, one could be bad. Swapping sides is a good idea to see if the code travels with the sensor. But as we speak the P0153 code has not returned for a full day. Don't know what I did but who cares! The P0151 code is still here. I removed the upper intake this evening, have to work on the street so I'm done until tomorrow. I removed the hard vac lines and will look them over real good. I'm gonna trace the evap lines and pull'em and look at them too. Any other vac lines I find will be inspected. Any lines out of the way, out of sight I might overlook? As far as the steam in exhaust, some days little if any, some days when really humid first minute or two I get quite a bit. Seems to steam the most when I top off the coolant level, once it drops it really doesn't do it. Strange... But the temp guage doesn't run hot. Goes up to just below midpoint. Will show cold in winter at startup so I assume it works right. I've been wondering if it really is steam or unburnt gas from cylinders that is being burnt in the cat, could it be? Maybe give off a smell other than typical gas smell? It is really rough at startup now all the time. I sometimes hurry the truck along in the AM, start and go really quick and that's the roughest. If I let it idle for aminutwe it is rough and low rpms then seems to catch stride and even out, better but not truly smooth. Sorry for the long reply. I'll post whe I'm thru tomorrow. Thanks for listening......Vic

 

Hey Vic - It is hard for me to diagnos the steam event you mention. A perfectly running engine will produce biproducts of CO2 and water. The CAT was invented to address the simple fact that we humans can't produce perfect combustion. It tries to mimic perfect nature chemically. And it does a great job on start up when an engine is cold. The O2's are dormant so the CAT can show it's stuff. A good running engine will always pump a little "steam" when cold. Especially after a 2 miunute wait at a traffic light. When the humidity is high, no **** - oh can't say that word - there is extra moisture in the air and it get's turned to steam out the exhaust.

Well - I'm getting bent on your codes versus the symptoms you are telling me. It would be great for me to see the issues you are witnessing but I guess we'll have to rely on text at this point.

 

I have checked intake manifold gaskets for air leaks by spraying carb cleaner aroung the intake while the engine is idling, if you have an air leak you will hear the idle speed change. Do not try this on a hot engine, wait until the engine is cool for safety sake. Good luck.

 

Well guys I put'er back together. No apparent cracks in any of the hard plastic lines. I bent and twisted them pretty good looking for a leak. Nothing found on the rubber lines either. I removed the rubber upper intake gaskets, wiped them off and reinstalled them. I did find that the mounting studs for the intake were loose in the fuel rail so I tightend them. I did not remove the lower intake manifold but I did retorque the bolts. No cracks or leaks in the breather tube. No steam or smoke on startup today, it's 90+ and pretty humid. Exhaust has no coolant smell. My neighbors must think I'm nuts sniffing car exhaust! Seems a little better but maybe it's wishful thinking. Took a 10 mile test drive and still have P1151 but no O2 codes. I need to pass inspection in July and the P1151 code will trip the MIL and that's automatic failure here in NJ. So I'm still looking. I want to thank you guys for the input, it's what makes this forum great.

 

Is it still running rough when cold? Since when cold, it will run in open loop control, the O2 sensors can not contribute to a rough cold idle. A vacuum leak will do that. But you couldn't find any apparent leaks so let's rule that out for the moment. A vacuum leak will also lean out right and left banks and you're just getting the code for one of the banks. So even more evidence against a vacuum leak.

Could it be you have mulitple problems? Possibly. You just did a tune up so the low hanging fruit's been picked. What about the IAC valve? Maybe the EGR Differential pressure sensor? These can cause a poor idle. Start thinking about other things that can affect the symptoms you are seeing. I think you said it was running rough before you started all this work so I would think that nothing you have done so far has caused it to run rough. Therefore the problem causing it to run rough is something you've yet to work on.

Now back to the vacuum discussion. Just for kicks to eliminate the brake booster, pull that line and plug it on the manifold. You can drive it around you neighborhood and whatch for codes. Now when you get the code back, hook the line back up and let's forget about vacuum leaks. At this point, I don't think you have a vacuum leak.

Reason is that you are only getting a code on one side. The only way for this to happen is if you have something wrong with a cylinder on that side. If it's something above the intake valves, it will affect all cylinders because they are then all connected by the intake manifold. So you may have a head gasket leak - either to a water passage or to the outside world. So you need to look for those signs. As you mentioned- steam out the exhaust, coolant levels, bubbles in the coolant, spark plug color deltas.

By the way, if you keep disconnceting the battery, the PCM will not keep seeing the lean signal and will not start building a correction factor. Afer a while, the PCM will believe a true lean condition exists and will then richen up the entire bank, whether you have MFI or SFI, because it doesn't know what cylinder is lean so it boosts all 3. So after a week or so of driving, your plugs will start looking black. They have to because that is how the PCM is programmed. Now when you get to this point, and if you do have a head gasket leak, you will have 2 black plugs and one white/tan plug. And wolla, there is your problem.

So Vic, outside of a head gasket, the only other reason I can think of for getting the lean codes is you have a bad sensor. This has happened to me. It wasn't as new as yours but had about 20K miles on it. Did you ever swap the R/L and see if the code moves to the other side?

-JEFF