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Discussion Starter · #1 · (Edited)
Another idling problem... now only when warm! Please help me!!

I hate to start another thread, but I am getting tired of this. My 2000 ZX3 is having idling problems and is now popping a Bank 1 Lean dummy code (I think it's P0171). I have the data logger/tuner from FocusSport. Is there any thing I need to be looking at? It is set up right now to log RPMDSD (1040), IACDC (0.38-0.40), LONGFT1 (1.24), RPM (1010-1040 sometimes up to 1110), and TP_V (~165.00). I just replaced the MAF and the upsteam O2 sensor and about to change the spark plugs. Any help will be appreciated!!!
 

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The last time I replaced my MAF , I had the same problem. They must be making them In ChinMexiwian . The actual base of the MAf wasnt flat causing an intake leak. Make sure it is completely sealed .
 

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I go over this tons of times, like a broken record, or skipping CD.

First off, before you go assuming your vehicle has deep problems that require the replacement of expensive parts like MAFs, O2 sensors, or ECUs- you should do what I call routinely overlooked routine maintenance, or an extended tune up. Of course, if this has been done in the last few weeks, then it's not a problem.
1) Plug wires: lifetime warranty from a national chain store so you can replace them at will whenever you have any sort of issue without costing money.
2) Plugs: OK, don't just pull them out and put new ones in. Pull each out, make a note of the deposits on the plugs, look for anything- color, buildup, type, etc that might be different about those spark plug deposits. Spark plugs analysis is very important for determining what is going on inside the combustion chamber. Platinum and other rare earth plugs are better at resisting deposits than standard plugs. If you're having continuing problems not related to something you can easily find and need to see if you have a problem on one cylinder only- then use standard plugs for a while so you can see some deposits. If you're unfamiliar with spark plug deposit analysis, then do an internet search for charts- look for more than one, as some I've found online are not so good or specialized towards FI applications.
3) Air and fuel filter: fuel filter especially is overlooked maintenance and should be replaced every 25k miles on every vehicle, every manufacturer. If you don't, then fuel pump life is greatly reduced. I'm now experimenting to figure out if my fuel pump will last longer than 100k (it already has) with regular fuel filter replacement. Air filter- no need to replace unless it's dirty, but you need to look at it and the housing to be sure everything is correct. There are plenty of running problems caused by loose air intake/air filter housings.
4) PCV valve: OH yeah, over 10 years all rubber breaks down. On Zetec engines, the main culprit we've found for vacuum problems is the PCV vacuum line. PCVs should be replaced or inspected with every tune up, and is another often overlooked routine maintenance part like the fuel filter which is supposed to be replaced every 20k miles. Expensive- no, like $5 at the most. The vacuum line going to it is most often the cause of many old Zetec running problems. I recommend removing the line completely from the vehicle to inspect it fully- the rubber elbows especially need to be folded to expose cracks or damage. If black rubber rubs off on your fingers- then just replace those already. Most parts stores have the elbows, or you can get the whole line from Ford for $20, and you can also replace the line with rubber vacuum line or fuel line as long as you don't make sharp bends that cause it to kink, or lay it up on the exhaust somewhere.

After you go through these things, and still have a problem- then ok, time to maybe replace something. I would clean things first. Low idle problems that are not vacuum leaks (there are other vacuum lines to inspect besides the PCV) are usually the fault of the IACV, but I don't recommend replacing it until after you've tried cleaning it and reinstalling it. It's a simple solenoid valve. Clean the shaft with carb cleaner or alcohol or even WD40 penetrating lube, and make sure the valve is sealing. If the valve is not sealing the chambers- then it needs to be replaced.

I prefer to attack all repairs by cleaning, inspecting, and replacing as little as possible while covering typical problem causers in these systems. You'd be surprised what totally dead vehicles I've repaired by cleaning stuff and replacing a few broken vacuum lines. Typically if a person pipes into a car repair conversation by saying, "Oh that happened to me just replace this and everything will be ok" they don't know what they are talking about and likely paid someone to figure that out for them. A good mechanic will tell you how to test things to be sure you are replacing the part that is actually causing the problem. The same symptoms can have multiple causes, so test test test, then repair what's broken.
 

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Discussion Starter · #4 · (Edited)
The MAF and the O2 sensor I replaced because of the dummy code I was getting and I know that they are the original parts (and nasty!) Air filter is a new K&N cone and the fuel filter should have been replace, but I need to check on that. As for the PCV valve I just bought one and cannot find were it goes... looked through the forum and even in the manual and all I get is a general area. I always am afraid to clean the engine w/all the horror stories I hear. What would you recomend to clean it? And what type of hose does the vacuum lines use?

-Edit 1-
I do change the plugs and wires, oil and fuel filter, and also clean the aire filter often.

-Edit 2-
Found an article on the pcv hose. Hopfully able to replace tomorrow... how doy you replace the valve?
 

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Discussion Starter · #5 · (Edited)
Ok... changed the PCV valve, coil pack, spark plugs, and wires.... still having the same problem. Going to go ahead and re-replace the fuel filter (maybe it was bad?) and hope that the problem get's better. Is there anything else that I am missing?

Also - she runs fun while warming up, it's just when she gets to normal temp that she starts having an erratic idle. She will idle @ her norm and then drop to ~200rpm, lights dim, and the battery light kicks on. She hasn't acctually stalled since I changed out the coil pack & reset the computer, but she has been getting close!
 

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Discussion Starter · #6 ·
I didn't your post irco34... I'll check that later today. Thanks for the heads-up!
 

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PCV valve: OH yeah, over 10 years all rubber breaks down. On Zetec engines, the main culprit we've found for vacuum problems is the PCV vacuum line^^^^^^^. From WNTWN. Seems like always an issue with the Zetec.
 

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^^ It's the PCV line not the valve itself, although the valve should be changed periodically. There can be other culprits- any vacuum leak. For example, if your brakes are hard to push, bad engine idle, then your vacuum leak is the brake booster. It's not like there's a lot of vacuum to check on these cars. Follow the schematic on the sticker on the bottom of the hood, trace vacuum from the device, like the carbon canister, to the intake manifold.

If you can't find damaged rubber (hard plastic lines are usually ok unless melted), then you might want to see about checking the torque on the intake manifold. I have had some cars that have loosened the intake manifold bolts over the years. AFAIK, there isn't any coolant running through the Zetec manifold, so you might not have any other signs besides lean conditions.

Before you go through the trouble to do all that: let's check an oddball issue. Look around on the top of your engine and find the grounding wire that goes from the firewall to the cylinder head or intake manifold. If you can't find one, then you should add one, and I'd add it to the intake manifold, a good place would be to put one under one of the hold down screws for the injector rail. I'd also make sure that the grounds coming off the battery and going to the chassis are good and securely connected on both ends. Check your battery voltage with the engine on, and engine off. Some people have had funny idle issues just before the alternator crapped out.

Also, you changed your spark plugs without reporting what the deposits on the plugs were like. That's a very important diagnostic clue. I don't diagnose engine running problems without looking at plug deposits when I'm there in person, and I really can't gather up what's happening when I don't have that clue in an online diagnosis. If the plugs are fairly new and platinum or iridium- don't bother looking, there won't be any deposits.
 

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OH, stupid me, I forgot, reset the computer by removing the neg terminal for 10 minutes, replace it, then start and without touching the accelerator, allow the engine to idle for 5 minutes after it drops down out of cold start idle. It should settle at 1k rpm, then after the test is done it should drop to normal idle speed.
 

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Discussion Starter · #10 ·
Sorry, I did replace the PVC line as well. It was not bad looking (no holes/cracks that I could see) but was weak and was very easy to pinch shut. The only ground that I could find on my engine goes to the eyelet that I assume is there to lift the engine out of the engine compartment. And the number 1 spark plug has some oil on the upper threads but none close to the element itself (<- taking that as a leaking valve cover gasket, right?). Sorry about not posting all the info, but I am doing this primarily at work and get distracted easily. I also rest the computer like you said to do and it was fine untill I drove it for a while... then it started again. but not nearly as bad. Thank you all, again, for your help!
 

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Discussion Starter · #11 · (Edited)
Talked to my father (he's getting certified on this "stuff" as he put it) and he said that it also could be the crankshaft, camshaft, and/or temp sensors... any truth to this?

Now he says to check the TPS, coolant temp, and O2 sensors... UGH.
 

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Ok... changed the PCV valve, coil pack, spark plugs, and wires.... still having the same problem. Going to go ahead and re-replace the fuel filter (maybe it was bad?) and hope that the problem get's better. Is there anything else that I am missing?

Also - she runs fun while warming up, it's just when she gets to normal temp that she starts having an erratic idle. She will idle @ her norm and then drop to ~200rpm, lights dim, and the battery light kicks on. She hasn't acctually stalled since I changed out the coil pack & reset the computer, but she has been getting close!
IACV. I had this exact problem. My car would run fine when cold but as soon as the car warmed up the idle would drop every time I stopped. Replaced the IACV with one I had on a spare motor and the car ran perfect after that.
 

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Discussion Starter · #13 ·
So I've also noticed she doesn't like to idle when warming up in the mornings and she smells like she's burning rich but she pops the CEL saying bank 1 lean... and I am leaving for a 12 hour drive here soon...
 

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Discussion Starter · #14 ·
LOL, OK. I just replaced the TPS and for got to hook it back to the harness... and poped 2 codes. One was telling me to reconnect the TPS and the other was P1131 (something about it missing a HO2S too lean). The HO2S has someting to do with the MAF don't know how though. This problem just gets more and more interesting! I still have to check the IACV...
 

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Discussion Starter · #15 ·
Ok, thought I fixed it, but when I left Ohio to go back to Ga the car actually stalled on me multiple times! Thankfully I have a manual so it just kicked back on. It was only stalled for a second each time not even time enough for me to take it out of gear... any suggestions? She is going to the shop but because of the 'winter storm' we just had most (if not all) of the shops are closed around here.
 

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Discussion Starter · #16 ·
Took it Tia shop and they said it was a fuel pump issue... that was last week. This week it stalled again. I'm now thinking electrical. But where to start? Any help?

Sent from my PC36100 using Tapatalk
 

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Talked to my father (he's getting certified on this "stuff" as he put it) and he said that it also could be the crankshaft, camshaft, and/or temp sensors... any truth to this?
H.
Crank or cam sensor bad= engine doesn't start. That's all there is to that. Yours runs, therefore you don't have a crank or cam sensor problem. The ECU uses the same temp sensor as the gauge in this vehicle, the gauge actually gets it's information via the ECU.

You never cleaned your IAC. It's under there with the PCV on this vehicle, except that it's actually attached to the intake manifold. Problems maintaining idle are often this part. Did you ever screw around with the screws on the throttle linkage? If you didn't, don't, if you did, tell us so we can tell you how to put that back like it should be. It is not an idle screw.

You could also replace the IAC, but I think you've replaced enough parts already. If you see any damage to the plunger, then you'll have to replace it.

What do the spark plug deposits look like? Is that the only DTC you're getting?
 

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Discussion Starter · #18 ·
I am not getting an codes right now it just stalls. It used to be a rough idle and stalling at speed but just today it stalled out of gear and slowing down. No codes, just a continuous drop in RPM all the way down... real smoth, too. As for the IAC; I thought that the mechanics looked at it while they had my car, but I don't see a charge for it on the bill. I will hopefully have a chance to look at it this weekend... As for the crank/cam sensors - I thought that it wouldn't start if they were bad, but my dad was saying that it could be that they are going bad and the heat from the engine is shorting them/it out. I am continuosly looking for vacuum leaks... but how many vacuum hoses are there on this car? And one last thing... where do you find the throttle linkage? (not that I want to mess with it, I just want to know where it is so I don't.)
 

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Discussion Starter · #19 ·
Ok, here is the current run-down:
Rough idle @ low speeds in neutral (normally less than 5mph), Sluggish response when accelerating in 2-4th gear from about 1000rpm idle (doesn't happen when I am driving normal), the electronics in the inside of the cab shutting off randomly, I do get the cog looking circle with the exclamation point in it come on every time the interior electronics dies but, as far as i can tell, the headlights don't die, and it still stalls did it to me this morning and instead of it kicking back over with just a slight hesitation i lost about 10mph.
I am think it is an electrical fault w/a vacuum leak (and the IAC getting stuck). But if it is electrical in nature should I look at all of the relays? Or could it be a simple as the ignition switch is bad?
 

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Have you done a compression test? If your dad is learning all this stuff, maybe he already had a compression tester. If not you can rent a "leak-down test" kit that comes with a compression tester. It should also come with directions, but it's fairly simple. Disconnect the fuel cutoff switch, or pull the EFI relay/fuse to stop fuel delivery. You can also do what's called Emergency Start mode where you hold the accelerator to the floor while the key is in the OFF position, and holding it there while starting. This prevents the injectors from firing- but has to be done every time you crank. Now unplug the coil to prevent spark. Remove spark plug, and install compression tester. Go crank engine with key for a few seconds. Do this with all 4 cylinders, and write down what you've measured. If you find one to be completely different, double check it, and write down what you've found on all 4 cyls- then bring that here. Typically if you're over 100 psi, and all cylinders read within 10% of each other- you're good. You probably won't get the exact same readings as are in your manual- your engine is old, the tester is not perfect- just wanted you to know that so you won't be dismayed. I would expect your readings to be within 25% of those readings though. For example (and this is way high), if your factory compression is supposed to be 200 psi, I wouldn't be worried if it showed 150+.

If you have electrical stuff shutting off inside the car, that might be another symptom of the same problem. Look at the negative battery terminal and make sure that there are at least 2 small grounding wires connected to the neg battery terminal with the big wire that goes to the engine. Verify that the bolt holding the big neg wire to the engine is tight, and verify that the neg terminal is tight. Usually grounding problems are there at the source. There should also be a grounding strap that goes from the engine to the firewall- on Zetecs I think it's at the back of the cylinder head, and looks like a shoelace. Make sure that is good, if not add another wire for supplemental grounding to the chassis.

There is nothing wrong with removing the crank position sensor and cleaning any crud off of it. That crud might contain metal flakes, and is confusing the sensor. I don't think it will make a difference, but you can't hurt anything by satisfying dad's curiosity. If I'm wrong and that fixes everything- then I'll have to send him a formal apology, but my experiences with magnetic sensors are that those either work or don't. No in-between.

Finally, you could be having TPS problems. The throttle cable is on the throttle body. It might be hidden behind some plastic cover. DO NOT mess with the screws on the throttle linkage. Those are not idle screws. If someone has screwed around with them, let me know and we'll give you a procedure to get it back to where it should be as best as we can. That will cause all sorts of problems once you finally figure out what is causing your problem.
 
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