Just bought a 2000 D2, 215k miles. I am the third owner (second owner bought it with 61k on it and then put 150k+ on it himself). Knew going into the sale that it would need work, which is fine. I'm OK turning a wrench. It's in great shape from an appearance standpoint.

The most concerning issue is rough idle, coupled with the 1171 and 1174 codes. Reading many threads in this forum, I see that it's insanely common to get those codes, and one or two threads posted their fixes, but most trailed off without a clear fix.

It seems most likely to me that there's an intake leak, but other potential culprits seem to include O2 sensor issues, MAF issues, fuel pressure issues, and maybe even purge valve issues (though I don't have any 044x codes. What other things do I need to consider in diagnostics?

This weekend I'll try a DIY smoke test to see if anything jumps out in the leak department. Haven't ever done that, but I'm sure I can figure it out. What is the best place to inject the smoke on D2's? Anyone have a favorite DIY smoke setup?

I am not going to replace them yet, but I have a new set of O2 sensors because a) the prior owner drove it for 150k miles and doesn't remember changing the O2 sensors, and b) as far off as it seems to be running right now, seems like there's a good chance that the O2 sensors are fouled at this point no matter what. I'll try to locate a definitive culprit before I change them though.

I'll attach a few diagnostic photos so you can see what I'm seeing. Observations:

1) it idles rough, and generally gets rougher once it's warmed up good. Right after a cold start, slightly elevated rpm (as expected) and not so rough
2) the trims at idle are all pegged at 25% on my live data. If I accelerate away from a stop sign, the short trims both go down and go negative while accelerating. At speed and backing off the gas, the short trims go back and peg at 25%. Long trims stay at 25% pretty much all the time, cold, warm, stopped, accelerating, etc. The trim screen grab was done while accelerating, and the 'valleys' on the short trims all associate to an acceleration event of some sort.
3) the O2 voltages sit pretty near zero at idle, but go up and down while driving around town (start and stop type driving)
4) the MAF shows maybe .5 lbs/min at idle, and goes up to maybe 6 lbs/min or so when accelerating. Kind of in the 1-3 range while driving. It did register one spike up to 55? These numbers seem a little low to me (and 55 seems high), but I'm not sure what they are supposed to be yet.
5) it runs smooth while driving. definitely still a problem at speed based on the trims data, but it's not sluggish or stalling/surging, etc. Nice and smooth and good power

Prior owner said he chased the rough idle some. Did new plugs, wires and coil packs, said he did the injectors (but I have no way to verify that). Said he did the valve cover gaskets. He said he had replaced the MAF sensor while he owned it, but not while he was chasing the rough idle.

I'm going to start with doing my best to detect intake leaks, but will welcome other DIY checks people can think of.

Other things I need to chase on it:
The power steering is not good. It has a new power steering pump, and I can see fluid circulation in the reservoir, but taking a little fluid out of the reservoir let me see that the filter that should be in place at the bottom is partially gone. Wondering if some of it is partially blocking the lines. Don't really notice much of a problem while driving it, but navigating the driveway, especially turning to the right, it's an arm workout.

The brakes seem a little soft to me. Brake fluid reservoir looks good, but that's as much as I've looked at so far. No issues stopping, they just don't feel 'strong and responsive' on the pedal push.

The ignition switch failed (key sticking issues, seems somewhat common on these). He had it disassembled so that he could start it, and I have a replacement barrel on the way.

There is definitely oil down low. Not enough to make a puddle on the floor, but the oil pan area is not dry. I don't see smoke or smell oil burning. Need to dig around a bit, but are there any common oil leak issues I should look out for?

Sorry for the long post, and thanks in advance for any advice. Looking forward to breathing a second wind into this truck. Looks and feels solid.

 

It fix those codes for me when I changed the injectors. In my signature youll find DIY smoke leak test. Good luck

 

Smoke test is a good starting point.

Also, I duct taped the nozzle of my vacuum cleaner to the exhaust tailpipe (obviously with motor off and pipes cold) and turned on the vacuum.

With the hood up, I was able to easily hear an exhaust leak in my downpipe connection (I had a broken stud in the down pipe).

Easy fix. Heck, easy test.



So those are good things to do first. The whole concept of *testing* instead of chunking parts as guesses at problem is a good way to begin.

Always test first if you can!


Now, the above being said, 25% long term fuel trim means that you've got a fundamental problem.

Do you have a scanner or app that shows "Open Loop" versus "Closed Loop" status? My Foxwell NT510 shows that.

What happens is that when the ECU detects enough of a problem that it can't correct, then its "Best Guess" is to go full rich in Open Loop mode.

...and that's treading close to Limp Home Mode next (stuck in 3rd gear).



If you have a scanner that can reset the learned fuel parameters, then that will be a good step to take next. That's much better than just resetting the OBD2 error codes (though doing that just one time after you've read them might be a good thing to do, as well.



Also, for less than $20 you can purchase a borescope that plugs into your smartphone.

Do that and run an app for it while you snake that little scope camera into each of your spark plug holes (i.e. remove 1 plug at a time... obviously motor OFF and cold).

What you are looking for are any "steam cleaned" pistons. That might suggest coolant getting into your combustion chamber.

If your pistons are all super black dirty then a coolant leak from a bad head gasket or cracked block is almost not possible... because coolant in that chamber will steam clean them. Looks good, but is bad.

 

Perhaps the most common fixes for those P1171 and P1174 error codes are new fuel injector baskets+o-rings.

Others have had success with replacing the $15 Hyundai purge valve which is an easy part to reach up top without removing a lot of gear first.


Just some data points. You should still do the smoke+vacuum+borescope tests first.


I'd *guess* that with the key in the ON position but motor off, that the fuel rails would be charged up by the fuel pump.

Any fuel dripping down into the combustion chamber would then suggest leaky fuel injectors... visible via your borescope through empty spark plug hole.

 

Gerry, thanks for the link for the smoke test. I'll run over to the home improvement store and see if I can come up with the pieces. Going right in the intake seems the most straightforward approach.


I might give that a shot. If I put the shop vac outside and closed the garage door, it might be quiet enough in the garage to hear a hiss.


My scanner shows fuel system status. It is telling me:

System A: Closed Loop - using all O2 sensors as feedback for fuel control
System B: Open Loop - has not yet satisfied conditions to go closed loop (Bank 1 or both)

I don't know exactly what that is telling me yet...

I'm not sure if I can reset the learned fuel parameters or not. I'll check that out. I did reset the codes on Wed. night, and have take a couple short trips around the neighborhood since then, and the codes came back today.


I have one, just not for my phone. It's a dedicated unit with a removable display. It is charged and ready for duty this weekend. I'm always fearful of working around the plug openings, but ya gotta do what ya gotta do I guess...

 

Oh yeah, about that borescope test...

Good spark plugs are just $2. Buy 8 new plugs and gap them to 0.40 per spec. After removing the old one, why reinstall a $2 used part when you just gapped a new plug to the proper value?

Go with the new spark plugs when reinstalling.

 

Prior owner told me he did new plugs wires and coil packs recently. The plug wires look newer to me. I pulled one plug last night, and it also looks like a new plug. It is an E3 brand (I wasn't familiar with that brand, so had to look it up) and was in very good shape. It is permanently gapped (not adjustable).

I ran the scope in that plug port, and it was definitely not steam cleaned. Looked like lots of combustion happening in there...

I'll wait until I can get a smoke/vacuum test done today before going further down the road with plugs. At least from that spot test, seems like he was telling the truth that plug work was recently done, and that a coolant leak of some sort is less likely. If a smoke test doesn't reveal any obvious leaks, then I'll pull the rest of the plugs and inspect with the scope.

Any thoughts based on the fuel status message I posted. I'm not an experienced troubleshooter. While everywhere else it is reporting Bank 1 an Bank 2, which I understand, I'm not sure what it's telling me with 'System A and System B', and what an open loop condition on System B might indicate that I should check out (other than getting a leak test completed).

 

Results of vacuum test, definitely a leak at the right side exhaust manifold to pipe gasket. One of the nuts was loose (could spin it with my finger). Tightened it up, but leak still present. New gasket for each side on the way (even though only right side seems to be leaking). Don't think there's anything I can do about it until new gaskets arrive.

Think that one leak could be enough to throw the kind of results I measured?

 

Not solely. Contributor, maybe.

 

And you would be correct. Smoke test had some smoke coming up from the underside of the intake manifold. Looks like I'll be learning how to rebuild the injectors...