Ok guys, I need help. I’m at the end of my skills with this. Back in november when we had the cold snap, I pulled the Max out of the garage one morning and it wasn’t running right. It had been sitting for about 2 weeks and ran fine when I parked it. Anyway, I figured it was running poor because it was cold and just headed off to work. Well, as the car got warmer the symptoms got worse. It had almost no power, I had to rev it high and get out of 1st to get moving. Near the end of my commute, it was backfiring on acceleration. I could hear it travel through the exhaust under the car.

I wasn’t quite sure where to start, so I just started checking things over. I found that the #4 coil pack was cracked all to hell. I replaced it with a new one from autozone (they are Nissan OEM) thinking that was the issue. Well, it wasn’t it. I continued poking around. The ECU code is O2 sensor. That sorta makes sense as it was backfiring, so there was unburned gas in the exhaust system. On this line of thought, I continued to check the ignitor system. I verified that each coil pack generates spark. At this point, the runability seems to have gotten worse, it will start, but will die if the rpms are taken to say, 2000 and let off. It ifs warm, it won’t start right away, but if let sit for 5 mins or so it will start again. The exhaust is a little strange sounding, it used to be deep and a bit rumbly but now it seems like its fast paced.

Thinking that it was still ignition or timing related, I swapped the ‘distributor’ with the one from my spare engine. It didn’t help. I also swapped the voltage regulator. Also no impact. Moving on to maybe it was an intake issue, I swapped the MAF. It didn’t help either.

At this point I’m completely lost. Anybody have an idea or two??

 

hmmmm...maybe a vacuum leak. The cold weather may have made a hose contract and crack.......also could be gas from sitting aroung...or maybe coolant temp sensor....................sorry thats all i can think of for now

 

try unplugging the o2 sensor and coolant sensor. It may or may not change the behavior if they are bad. Id replace both though as they arent too bad in price.

~Alex

 

Maybe an injector issue since you have unburnt fuel in exhaust and some backfiring issues. Check you oil and see if it smells like gas or the level has risen. Is it missing also? Just some thoughts

 

if you have an O2 code you should take care of that and it might fix the problem but also check fuel pressure you could have a weak pump or very clogged filter

 

I forgot when I wrote that. Using the FSM, I had determined that the coolant temp sensor might be the cause and pulled the one from the spare motor I've got. That didn't have an impact and it was one of the 1st things I tried.

I'm hearing you on the o2 sensor, but I figured that it was fouled by unburt gas in the system for its poor running. Its a resonably new sensor, I installed it about 18 months ago.

Its not bad gas, as gas doesn't go bad in a couple week time frame. I could change the fuel filter though, I've got one on the workbench. As for testing the fuel pump, I was having trouble finding a source for an in-line fuel pressure guage. I guess I've not looked that hard though...

 

Have you tried pulling coil pack harness or injector harness one at a time as the engine is running, i.e. cylinder balance test. Since you've already tried a different 'distributor' maybe it's fuel related, maybe an injector is stock open or not working properly.

 

are you sure the parts off your spare motor are good?

 

If the coolant sensor is bad it will cause your fans to run continuously. If the MAFS is bad the ECU will not allow the engine to rev higher than 2400 rpm.

 

CandiMan: *sigh* I did that too.. One of the 1st things. each coil that I pulled the harness from almost made the engine die. Balance seemed as I would expect.

internetautomar: Well the engine ran fine when I pulled it despite a slight exhaust manifold leak. I don't see why the parts would be bad.

Grace_Imports: Thanks for those tips. I don't have either of those symptoms. At least I can feel good about ruling those items out!

 

At this point your choices are getting limited as a DIY's without any diagnostic tools. This is what I would try

1) do what it takes to fab up a in-line fuel pressure gauge
2) I agree with what you're saying about the o2 sensor, but for testing purpose I would swap out the o2 from your spare engine.
3) swap out the ECM

If the above doesn't make a difference you may have to bite the bullet and pay to have your car's ECM put on a scaner.

This is a pic of my fuel pressure gauge I installed many moons ago.

 

I think its the fuel pump. I realized that I couldn't hear it when key was moved to the run position. I then changed the fuel filter and the fuel just dribbled out - and I dind't pull the fuse and let it die, it was supposed to be under pressure.

Between those 2 things, I think its time to get a new pump... Walbro?

 

When you pull back the rear seats, don't be surprised to find this. I had a fuel pump harness connector go bad with absolutely NO prior warning signs, for years. One day after work it would crank but no start. Funny thing, I've never heard or seen another 3rd gen with this problem, so I figured this was a one of problem. I'm also running my original fuel pump so it's not like I had a after-market pump that's pulling higher amperage.

 

ok, so no fried fuel pump connector and a new fuel pump.

but the friggen thing isn't right. Its not as bad, but still will bog. I can quickly floor it and the RPMs will go to about 600 and it will just sit there and chug, when I let up, it goes to about 1500 and then back to idle. If I raise the idle slow, it will go to redline without issue.

I've swapped the o2 and the ecu at this point.

The dealer is 4 blocks away, I might as well take it there and have them tell me what is wrong. They'll just ***** about the tranny swp and the alarm install though. I guess I could always set it on fire and just walk away...

 

Possibly faulty fuel lines? Perhaps clogged? If not that then I would definitely suspect an injector. Just throwing it out there.

 

I'm with you on this one, because one of these days you could be me.

1) Fab up a in-line pressure gauge, it's never a bad thing to have one of those.
2) I was going to suggest to put the ECM in the diagnostic mode to check the o2 sensor, but since the engine is running poorly it doesn't make sense to do that.


Back on the fuel pressure idea, maybe you have a fuel pressure regulator that's going bad and it's not holding pressure in the rails. You mentioned when you pulled the fuel filter hose the fuel just dribbled out. Try pinching the return fuel line and see it that makes a difference while the engine is running.

 

I didn't get to play with it today. It was range time after work. Its supposed to be nice tomorrow, so maybe then.

 

"Its not as bad, but still will bog. I can quickly floor it and the RPMs will go to about 600 and it will just sit there and chug, when I let up, it goes to about 1500 and then back to idle. If I raise the idle slow, it will go to redline without issue"

i believe you could eliminate whether its a fuel or ignition problem by after doing the 'bogging' of the engine(dont get it too hot!!), start pulling the s.plugs. if its not getting adaquit spark, them pluggers will be a drippin'
have you checkd the sparkplugs at all when you replaced coilpack and 'dizzy'?

for fuel- fuel filter clogged? injector condition, injector pulse width but thats hard to get unless u have an occiliscope.

 

I think it could be a fuel pump. That might also trigger an 02 if the FP is so low, the injectors can't stay open enough to get the A/F back in line.

I might have an old fuel pump I can sell you for cheap if I can dig it up. I might have an old 02 but I doubt it.

 

Been there, done that, post #14

 

Yes Candiman, the new fuel pump was in-place and the old 02 was put back. It doesn't look like its the FPR either, as I just came in from trying the visegrip-on-the-return-hose trick that didn't help.

I decided to pull the codes again, but then realized the FSM isn't here. I pretty much remember the process, and it looks like a 13 and a 33.Can you get 2 codes at once? I'll have to look at the FSM when I get home tonight to figure out what they are.

Thanks for sticking with me on this one guys, I know I'll be happy once we figure it out...

 

Yes you can get multiple codes at the same time. Let's re-cap, you've

1)tried a different ECM
2)tried a different MAF
3)tried a different CTS
4)tried a different o2
5)new fuel pump
5)tried a different CAM sensor 'distributer'
6)tried a different ignitor 'regulator'
7)new fuel filter
8)new #4 coil pack
9)did a cylinder balance test, all cyl effected the rpm when unpluged

I'm still going to suggest to fab up an in-line fuel gauge. Maybe one or more injectors are leaking, possible o-rings or the injector pintle valves. There's a specification on how much pressure should be in the lines once you turn the key off and how long the pressue should be there.

You may not know this, but fuel pressure should raise right after turning the ignition key off. The gradually drop over time, if it drops too fast you have issues.

Have you pulled the plugs to see how they look, maybe one (or more) might look extremly different than the others, maybe one (or more) might be more saturated with fuel showing that there's a problem in that cylinder.

Even though you did a cylinder balance test and all cylinders made the rpm drop to the point of almost stalling the motor, you might have a fuel issue.

Here's my point
Let's say you're getting getting too much fuel in the cylinder, killing the spark will definately have an effect, but unless you're able to kill the fuel your cyl balance test will not be complete. Try unpluging the injector harness one at a time on the left bank and see what happens.

 

I've exhausted local shops for a fuel pressue guage that is acceptable for the engine compartment. I guess its just not that called for and most domestic vehicles have the screw-on valve. I'll order on-line this weekend.

 

Maybe you should try Home Depot or Lowes and fab up pressure gauge. I got my gauge and fittings from work many years ago so I'm not 100% you'll find what you need at the home centers. It's worth a shot

 

Tonight I pulled the plugs. Pics are below. Nothing too suprising, a little dirty but not too bad. One thing I thought was kinda strange, 4 out of the 5 are cleaner on one side than the other. Not head gasket is bad kind of clean, just not as brown. One of the pics below should illustrate.

 

While your vehicle is running, try spraying the vac lines, intake to head area and the big rubber pipe that goes from the MAF to the throttle body with some brake parts cleaner. It sounds like it could be a vac leak, you would be getting the wrong reading from the MAF then and it would cause the "bogging" feeling. When you spray with the BPC you should hear a rise in the RPMS. This will help you locate the problem area. A can of BPC is less than 2.00 so it's worth a shot!

 

Also, when you swapped the MAF, did you check the connector well and make sure there was no issue with spread terminals or a loose wire?

 

Is that oil on your spark plug threads? Id wonder how the oil got to the plugs. Hows the oil level? Check the valve cover seals. Theres a lot of oil under the valve covers and if the seals leak around the spark plug wells it can get all over the plugs, and that might short them out..

~Alex

 

Nah, thats not it. The oil you see there is the extent of it. Friday night I put new plugs in, and it ran pretty good for a while. In fact I thought maybe it had fixed it so I took teh car around the block after running it for 10 minutes or so. Well, I drove about 3/4 of a mile when the bogging returned. Its almost like when it fully reached opoerating temp - something I don't think it did before. I'll run it again maybe tomorrow and see if it is ok when cold and go from there. Thank god I've got other cars....

 

find someone to lend you a set of known good coils.
there have been many cases where even though they worked fine most of the time they would create some running problems.

 

When it's cold it will run in open loop mode substituting default values to make the engine run. After it is up to operating temp it uses feedback for the O2 sensors, temp sensor, MAF etc. to adjust the fuel and timing. Are you sure you don't have a vac. leak or bad connection at the MAF? With a bogging as you describe I've found that 90% (a rough estimate) of the time it is intake air related. Also, i've seen this sort of thing happen if the timing belt skipped one tooth. Have you checked your timing and made sure everything lines up?

 

Just a little insight on the VE motor, it has a timing chain (3 of them) and not a belt.

 

Ok, so that should read... have you checked your timing marks and made sure the tensioners aren't allowing slack. Sorry, I was generalizing.

 

I haven't yet. Its cold out there man...

 

Greetings,
A couple things.

First, add a bottle or two of dry gas (isopropal alcohol). It is very possible condensation has occurred in the gas tank.

Second, consider replacing the fuel filter.

Just my thoughts.

Tom

 

Dry gas maybe, fuel filter was already changed

 

Ok, guys thatnks for you help! Its running again. I'm not 100% sure why, but it is.

After replacing the fuel pump and the pressure and return hoses, I replaced the CTS and O2 with new, and left the electronic distributor unit in there that I had swapped in during the troubleshooting. I hit it with the timing light (finally) and it pretty much runs ok. I think I had a couple of issues, the fuel delivery being one of them but there was something else.

I wish I understood the problem better, but for now its all good.

 

Wow, you live in gurnee too. Thats pretty cool, not too many 3rd gens around here.