2001 Ford Focus ZX3, S2, 2.0 Dual overhead cam
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My issue started about 2 weeks ago. I was on my way home from work, ran into the gas station for some milk, and when I get in the car to start it it just cranked for several seconds before it finally started up. No issues for a week after this. Then last Tuesday on my home from work when I would pass a vehicle on the highway and it would start to surge and hesitate. I ended up missing my exit and had to do some city driving (about 30mph) the rest of the way home. While going 25-30mph up hill, it felt as though my car was falling on it's face. Once it got level I was going smooth again. So I pulled it in the garage and checked for DTC and fuel trim.
What I found at the time was no DTC's but fuel trim was at +24(lean). I monitored the vehicle's engine data saw that my rear 02 sensor wasn't giving me any reading. So I swapped my fuel pressure relay(per another forum post), replaced the 02 sensor, PCV, ignition coil connector (wires were damaged where they went into the connector), DPFE sensor (because of posts I saw on the forums), fuel filter and drained the tank got a few gallons from the gas station (in case it was bad fuel). After replacement , my rear 02 now gives me a reading, I have the same fuel trim reading(+24), and my fuel pressure is reading the same (30-35psi on my pressure gauge, 36-40 on the scan tool through the sensor). I continued checking for external vacuum leaks - none found. I did replace the tube behind the intake (connects to PCV, the tube really soft) and the tube from the valve cover to intake (just to change).
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Also, before I forget, I did test drive it after replacing the first set of components (prior to changing the vacuum lines) and it drove like crap. Anything about 1200rpm it feels/sounds like the converter is clogged or I have a huge exhaust leak near the engine where it would suck in air through the exhaust.
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So, I disconnected (and damaged) the egr tubing at the exhaust side and put my blow gun to it. Under light throttle/pressure with the blow gun I can hear it leaking into the intake. So, I deleted the egr to retest. Fuel trim numbers are now perfect at idle, they fluctuate between -2 and +4. So I think, ha I fixed it.....WRONG. I lower the car and pull it out of garage and I can feel that same severe hesitation on light acceleration (anywhere above 1200RPM) and fuel trim when it is running rough is again in the 20's (lean). So I pull the car back on the lift, apply a rod to the brakes (for light to moderate brake pressure), and put the car in gear. The car accelerates smoothly (up to around 2500rpm) and is going at about 60mph. I checked for exhaust back pressure, at idle it bounces pretty good but is in spec on the gauge. I increase the rpm and it stays right at 0 the hole time (makes me think cat isn't clogged). But at the dealer we would just disconnect the cat and take it for a run, so I did the same. Popped the cat loose after the flex and pulled it out - no difference, in the driveway or going down the street anywhere near or above 1200RPM it falls flat on it's face. After letting the vehicle idle in the driveway for about 2 hours I did have a history P1233 and yes I have searched forums and the web for that code and have ran as many tests that I came across related to that code.
By this time I have already checked plugs (look normal), checked for spark (all cylinders look the same), TP sensor operation and MAF sensor operation (using scan tool), checked injectors for operation at different rpm (using stethescope), checked injector operation doing a balance test (all injectors drop from about 45-46psi to 15-17psi), I checked compression (I'm at or above 150 on all cylinders), and checked plug wires for resistance ( I have the livewire plugs) the all read between 250-550ohm depending on length (you can see some arcing points where the plug wires over lay each other). Checked my original factory plug wires for resistance they are all between 2.5kohm-5.5kohm.
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I swapped out the screamin' demon coil pack and my aftermarket wires with the vehicles original - no change. By this time I also redrained the tank, and pulled the pump (I saw the posts about the fuel pump extended warranty, which mine expired a year ago). I already have the new redesigned pump, but the strainer/pump sock looks like crap. So they don't just sell the stainer kit, so I bought a new NAPA fuel pump and retested - NO CHANGE...
Now, we are about up to date. This last part was done last night and my brother was here to rev it up in gear for me while it was on the lift and I am starting to get it to fail there as well (hearing the occasional back fire as well). Clearly I don't expect anyone to be able to fix it through the forum for me, but clearly there is something I am missing or forgetting to check and that is where all of you come into play. Below is a list of some other things that I recall testing and then below that is a list of the mods that have been done and resent repairs.
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IAC: spec is 6-14 ohms (I'm getting 10.7 ohms)
Injectors: spec is 13.7-15.2 ohms (I'm getting 17.2/17.1/17.2/17.2 and I'm getting .1 across my leads, so average at injectors is right at 17ohms)
Injector Balance: 45-46 peak, dropping to 15-17 on all for
Compression: about 150-153 on all 4
TP: Normal flucation with voltage/percentage as the pedal is depressed (much like myself at this point)
MAF: normal fluctuation with throttle change
Plug Wires/Aftermarket: 250ohm-550ohm depending on length
Factory Wires: 2.5kohm-5.5kohm depending on length
Fuel pressure on my gauge/new pump:
Key on Engine off: 45psi
Running: 30-35psi
Fuel Pressure old pump:
Key on Engine off: 40psi
Running: 30-35
Fuel Pressure with scan tool:
Running: 40psi - average
STFT at idle: Near 0
LTFT at idle: Near 0
LTFT on throttle/when hesitation is present: above 20 (lean)
FPDM testing:
Battery Supply/Key on Engine off: 12V
Battery Leaving/Key on Engine off: 12V
Signal Voltage w/ key on engine off: Fluctuating between .3-8v

Parts Changed for this Issue:
Removed tune from vehicle and reset to factory (I have since moved back to the tune since it made no change)
Fuel Filter
Injector Connector
PCV
Rear 02 Sensor
DPFE
EGR Delete (fixed fuel trim levels at idle, but not drive-ability issue)
Fuel Pump
Plug Wires and Coil (swapped back to original/factory)

Recent Repair
Installed electric vacuum pump to brake booster and sealed off engine vacuum line (vacuum to booster was only at 15 psi and braking was weak, now vacuum to booster is near/at 20psi and I can lock up my brakes).
---I did disconnect the fuse to this pump in case the electrical draw causing this issue, but no change.
I did recently change the battery and removed my underdrive pulley and reinstalled the factory pulley - I did this because I am no longer on home dispatch and have to drive my vehicle about 31 miles each way to work.
New timing belt and tensioner about 1.5 years ago

Vehicle Mods
INJEN Inake (not cold air)
Crower Stage 1 Cams
Adjustable Cams
Livewire wire set/Screamin' Demon Coil Pack
OBX race head and MBRP 2.25" catback exhaust
--Modified exhaust to install cat (about 5 years ago)
SVT Brake Kit
SVT suspension
65mm TB


Anyway questions or info would help, right now I'm just grasping for anything. And for those of you who took the time to read through this book I've just written, THANK YOU...

 

You have done quite a job so far. For what it's worth , I am starting to wonder about the readings you are getting on those injectors. I think you may have one that is dropping out and may have affected the PCM. You have invested a lot of $ in this and you might as well do the injectors. What is the fuel trim at 2500 RPM ?

Something as simple as a sticking open PCV valve can cause a lean condition, but I noticed you changed it. What about the hose itself?
Does your freeze frame info narrow down the area and conditions where the lean condition develops?
What about a sticking/malfunctioning purge valve for the fuel system, once the vapors are drawn out it will be allowing only plain unmeasured air to get into the system.
Did you ever find out why you had to install a vacuum booster since the vacuum was sooo low?

 

Well, I swapped out the MAF and TB sensor(just in case they are doing something that I'm not seeing on the scan tool) - no change, so I put original back in. I removed the IAC and could see that the mounting surface looked extremely corroded, including the 2 little seals that actually seal the ports to the intake. So I replaced that, but no change (I will be keep this new part in the vehicle).
I then adjusted me cam gears to see if it would help adjust the vacuum level (per one of the techs I used to work with) I adjusted it about 4 degrees, but no change in drive-ablilty. Retested vacuum levels while in gear (reverse) at about 1000-1100 RPM and it is about 7.
So, I spoke with my dad and I'll be able to use his vehicle for a week. So, I stepped away from it and went in the house around 9 last night rather than midnight, like all the other days. The couple hours away from it may be whats needed. I remembered this morning that after deleting the egr and testing it my lean condition at idle was gone, it runs perfect...until it is in gear, outside. So, prior to replacing the fuel pump, I moved the vehicle outside and let it idle (in park obviously) for about 2 hours and went in the house. While it was out there I could hear it surging up and down and I was just waiting and hoping for what ever bad component to fail completely...as I told my daughter "dad needs his car to die, so that I can fix it".
That is when I went out there and had the history code for the fuel pump driver module (P1233) and after seeing how nasty the fuel pump strainer was I just stuck that idle surge with a pump that was starving of fuel. However, clearly it wasn't the pump. So I need to reconnect all of my test gear (fuel pressure gauge, vacuum gauge, and scan tool) park it outside tonight and let it run. Once I hear it surge, go outside and take a look.
In regards to your question I have replaced the vacuum line between the intake and the metal tubing that goes to the PCV that had to be one of the things I had done early on. As far as with the crower cams, I remember a warning on one of the sites that the cams would effect my vacuum levels and my idle speed/quality due to the lobe change. This is why I only went with a stage 1 and not the 2 or 3.
Another tech that I had work with said that it sounds like an intake leak, which is possible. But, I have sprayed so much brake clean around all the hoses and intake and haven't heard any change in idle or seen any fuel trim change on the scan tool. But clearly what ever is happening doesn't like the cold air, so I will redo this tonight or tomorrow in the driveway rather than in the garage. Possibly injectors, like you said...it definitely could be. The only things that it can't be at this time is egr, IAC, MAF, TB sensor, pcv, the couple vacuum lines I changed, plug wires/coil pack, coil harness/connector, rear 02 sensor (I know it's for catalyst monitoring,but originally it wasn't giving me any data readings), fuel pump/screen, or the original fuel that was in the tank....I wonder if I'm leaving anything else out.

 

I'm not sure if your vehicle has an electronic returnless fuel pump system , but if it does there should be a pressure sensor on the fuel manifold that sends the signals to the fuel pump driver module. The code is telling you the signal is not always there. Might be a good idea to look into this a little further.

 

Hi guys: I just went though the list in the original post. I did not see any mention of the Intake Air Temperature Sensor.

I too think this is a vacuum leak that Craze173 missed. I would try a different method of leak testing. A smoke test or up to 10psi pressure supplied to the intake.

In some cases Ford advises against a smoke test because some leakage is allowed and compensated for by the ECM. Just saying so you don't go over board fixing leaks.

 

non turbo use can carb cleaner spray can kind and does how does fill up obove 2500 rpm try check spark and I also had car come in with these problem he didn't have a boring on the fuel injector it self hope these helps my thoughts on it at the moment and mechanicle timing to does it halve variable valves are kinda like vetec or ecotec? If so could be it and pull radaiter cap check it to alot of new cars 90 up have proublums like these just from coolant systems

 

That is actually how I'm checking for vacuum leaks, by pressurizing the intake. Except I am only doing it to 3-4psi. Online i read that anything higher than that you risk making new leaks. As far as the valve timing, only the svt zetecs have vct. So, my cams/valve timing stays where ever i put it when adjusting the cam gears. I do have a programmer that allows me to advance or retard the ignition timing between certain rpm ranges. But I dont feel like that is an issue because it is showing lean and not rich when the problem is present. I did notice 2 leaks when i accidently got the pressure around 6-7 when trying to set the pressure. So, I'm not sure if they were existing leaks or ones that I caused from the higher pressure. There was one small leak, pin hole, from the bottom of where the egr was sealed. And there was a large leak along the back side of the TB gasket. I will recheck tonight after work to see if these appear to be sealed now as for as the iat sensor, when i tried searching for that part online I didn't see any results. So, I'm assuming that it is part of the maf sensor. I cant remember if i updated this post or not, but I did try a new maf, tps, and iac valve. None of them made a bit of difference, although the iac valve surface was completely corroded, i have no idea how it was sealing.

 

After i get it put back together tonight i will try the propane method of testing because i havent had a bit of luck testing with carb cleaner.

 

Well, yesterday I sprayed the crap under my hood (outside in the cold and in the garage on the lift) with propane and there wasn't one spot under the hood that caused the rpm to raise or cause the fuel trim numbers to go rich.
So, I remembered something that I had mentioned to my dad (and maybe some other people) a week ago. I had told him that I never hooked up and monitored the fuel trim numbers after doing the mods to my car, so I don't know if these numbers I'm seeing are bad or normal. So, I told myself I am not going to diagnose it based on that.
So last night I took off the valve cover to replace the seeping gasket (no change in idle or fuel trim when spraying around the gasket) and removed the spark plugs to replace them (about a year old plugs, still look pretty new).
Today I replaced that gasket and the plugs (with the more expensive diamond tip plugs) and it now drives perfect. My fuel trim numbers still look like crap with it in gear and my vacuum still looks like crap - around 6-7 with it in gear. So, for anyone else who has changed things with their engine, don't look at fuel trim numbers to diagnose a problem. There is a good chance that those numbers are like that because of the mods that have been done.
The only plus side to this happening is that I did do a lot of maintenance type things that would have been put off and would have given me a lot of trouble over the next 6 months. The ignition coil connector wiring was damaged (2 of the 3 wires were cut near the connector and about rusted in half), the EGR was leaking (wouldn't hold any vacuum when I tested it off the vehicle), the fuel filter was beyond due to be changed (the fuel coming out of it looked like muddy water), 1 of the fuel tank staps was about rusted in half, the pcv was sticking, the vacuum line from the pcv to the intake was weak (it squeezed closed with vacuum applied), the fuel pump strainer was dirty/pump was loud (would've been fine for another year or 2 though), and the IAC valve seals were leaking (the mounting surface was corroded past the seals).
So, as long as I don't wreck the vehicle anytime soon...knock on wood, it should continue driving smoothly for some time. Thank you again for those of you who have posted.

 

Congrats!
Thanks for the feed back. I have the feeling you and me learned a lot with this episode!

Happy motoring!