Diagnosis Needed

[MichaelH]

My '95 MTX is hard to start when warm and the idle surges up and down when between cold and warm. I've replaced the IAC and TPS. I ran tests and get only a 114 (which I think is only because it's 20 degrees outside), and in the stored codes, only a 211, which could be from cranking, then turning the key off, then cranking the second time to start, and a 542, which I think is also related to trying to start the car multiple times when warm. Although hard to start the first time when warm, it runs fine once it's started. I had a 136 a couple of weeks ago, but that didn't appear in this latest test. The CPS has only about 10K miles on it. I'm thinking maybe the CID sensor is bad when cold? Would a bad CID throw a particular code?
Thanks for your help in advance.

<small>[ January 10, 2004, 12:35 PM: Message edited by: MichaelH ]</small>

 

[masho95]

The CID sensor will sometimes throw a 214 code when bad, but not always. Did you reset the idle after installing the TPS and IAC? If not reset the idle and try again. The 211 code won't be thrown just from cranking and then re-cranking. The sensor is going again (check for WP leak) or there might be a problem within the wiring somewhere, causing an intermittant problem. I've seen that before on my buddies 89 where the PCM power cable coming from the battery was spliced, and badly at that. Accelerating and usually turning corners would put stress on the wire and cause an intermittant open throwing both a 14 and 19 code (CKP and CMP codes). BTW did you replace the IAC solenoid or the IAB valve? Anyways check out these things first.

 

[MichaelH]

Thanks for the ideas. I replaced the entire IAC/IAB and TPS and I did reset the codes. I didn't reset the idle. Didn't know you had to. How do you do that?

After the codes were reset, I ran the tests and got a 111, then a 136 from the KOER tests, but, like I said, no 136 this time. So these latest codes are from operations during the last two weeks since then.

I'm getting a queasy feeling that it's the water pump. I'll have to check it. The guy I bought it from replaced the CKP and timing belt at 44K, but not the water pump.

<small>[ January 10, 2004, 02:59 PM: Message edited by: MichaelH ]</small>

 

[masho95]

Just do a search on here for "idle speed reset" and you should come up with the correct info on resetting the idle speed. And there is a difference between the IAC and IAB. The IAB is the valve located on the top of the intake towards the driver side. The IAC solenoid is located by the driver's side firewall. And so did you got a CE light when running the car, which would be the 136, or a problem with a O2 sensor or something else causing the O2 sensor to get a lean reading. Look on the passenger side of the car below the waterpump and see if you can see any leakage.

 

[oh_SHO]

I have the same problem and have replaced numerous sensors and including the CID. Did it make a differnece? Heck no. I have come down to the fuel isn't holding pressure. Does it start everytime if you cycle the key twice? Mine does so I am running the damn thing until the pump quits. Which will probably be spring after I take it out of storage...

 

[MichaelH]

masho95:
Just do a search on here for "idle speed reset" and you should come up with the correct info on resetting the idle speed. And there is a difference between the IAC and IAB. The IAB is the valve located on the top of the intake towards the driver side. The IAC solenoid is located by the driver's side firewall. And so did you got a CE light when running the car, which would be the 136, or a problem with a O2 sensor or something else causing the O2 sensor to get a lean reading. Look on the passenger side of the car below the waterpump and see if you can see any leakage.

I see. I was never clear on the IAB/IAC thing. I replaced the IAB, then. I will look for the IAC.

I got the 136 after I replaced the IAB, cleared the codes, and ran the tests. I got a 111 on KOEO and 136 on the KOER. Even though I didn't get a 136 on the latest tests, I bought a new 02 sensor for the front just to be sure, which I will put on this week.

 

[MichaelH]

oh_SHO:
I have the same problem and have replaced numerous sensors and including the CID. Did it make a differnece? Heck no. I have come down to the fuel isn't holding pressure. Does it start everytime if you cycle the key twice? Mine does so I am running the damn thing until the pump quits. Which will probably be spring after I take it out of storage...

Yes. When warm, it cranks a long time before catching, then it stumbles a bit. If I stop cranking and try again, it starts right up. That's what led me to my first suspicion of the CID, but I don't get any codes which would indicate the CID. So, you think the fuel pump is on it's last legs?

 

[MichaelH]

So, I checked the CPS and water pump - dry and clean. No evidence anywhere of any leakage, which makes sense, since the car only has 54K miles on it and the CPS only 10K miles.

I'm leaning now towards the fuel pump, mentioned by oh_SHO who has the same symptoms.

 

[MichaelH]

MichaelH:

masho95:
Just do a search on here for "idle speed reset" and you should come up with the correct info on resetting the idle speed. And there is a difference between the IAC and IAB. The IAB is the valve located on the top of the intake towards the driver side. The IAC solenoid is located by the driver's side firewall. And so did you got a CE light when running the car, which would be the 136, or a problem with a O2 sensor or something else causing the O2 sensor to get a lean reading. Look on the passenger side of the car below the waterpump and see if you can see any leakage.

I see. I was never clear on the IAB/IAC thing. I replaced the IAB, then. I will look for the IAC.

I got the 136 after I replaced the IAB, cleared the codes, and ran the tests. I got a 111 on KOEO and 136 on the KOER. Even though I didn't get a 136 on the latest tests, I bought a new 02 sensor for the front just to be sure, which I will put on this week.

Could you be more specific on the IAC solenoid as to its location on the firewall? Driver side? Behind the outside cover? Autozone calls the IAB the Idle Air Control Valve, which is the part on top of the engine I replaced.

I did the idle reset. So far, no surging while driving today. Thanks. I'll keep my fingers crossed.

<small>[ January 12, 2004, 08:31 PM: Message edited by: MichaelH ]</small>

 

[pjtoledo]

masho95:
........ The IAB is the valve located on the top of the intake towards the driver side. The IAC solenoid is located by the driver's side firewall. ........

Hmm, conflicting info. Helm's manual, 95 version, page 03-14-02

The idle air control valve 1. controls engine idle speed and dashpot functions 2. mounted on the throttle boby and allows air to bypass the throttle plate. the amount of air allowed to bypass is determined by the powertrain control module and controlled by a duty cycle.

The manual states what was called IAC in '95 was previously called IAB, among other things.
Rebutals and additional info welcome.

We're talking MTX right?


Perry

<small>[ January 12, 2004, 08:51 PM: Message edited by: pjtoledo ]</small>

 

[MichaelH]

pjtoledo:

masho95:
........ The IAB is the valve located on the top of the intake towards the driver side. The IAC solenoid is located by the driver's side firewall. ........

Hmm, conflicting info. Helm's manual, 95 version, page 03-14-02

The idle air control valve 1. controls engine idle speed and dashpot functions 2. mounted on the throttle boby and allows air to bypass the throttle plate. the amount of air allowed to bypass is determined by the powertrain control module and controlled by a duty cycle.

The manual states what was called IAC in '95 was previously called IAB, among other things.
Rebutals and additional info welcome.

We're talking MTX right?


Perry

Right - MTX. Here's a link to the part I replaced. I don't know where the other part is that masho95 refers to.

http://www.partsamerica.com/PartDetails.asp?SourceArea=&SourcePage=SEARCHRESULTS&MfrCode=BOR&MfrPartNumber=21760&PartType=506&PTSet=A

<small>[ January 12, 2004, 09:31 PM: Message edited by: MichaelH ]</small>

 

[Electricat]

You should try cleaning the MAF sensing wires with some electronic contact cleaner, if you haven't already. I have known of several cases on Mustangs, and my own Ranger, of this being the cause of a poor idle.

There are plenty of other things it could be, but this is a cheap and super easy thing to try.

Just remember not to touch the wires, they are fragile!!

 

[masho95]

Sorry, about the conflicting info on the IAC... I think I confused myself when talking about it. I think I confused the IAS for the IAC. Disregard the info that I posted on the IAC.. sorry again, didn't mean to have you running in circles.

Edit: When I had pulled my intake a few years ago I accidentally left the IAS connector off, which resulted in a very erratic idle and threw a 551 code which I quickly found my problem.

<small>[ January 12, 2004, 10:04 PM: Message edited by: masho95 ]</small>

 

[MichaelH]

masho95:
Sorry, about the conflicting info on the IAC... I think I confused myself when talking about it. I think I confused the IAS for the IAC. Disregard the info that I posted on the IAC.. sorry again, didn't mean to have you running in circles.

Edit: When I had pulled my intake a few years ago I accidentally left the IAS connector off, which resulted in a very erratic idle and threw a 551 code which I quickly found my problem.

That's OK. Thanks. I keep finding out about stuff I had no idea existed, so it wouldn't have surprised me if it was there.

 

[MichaelH]

Electricat:
You should try cleaning the MAF sensing wires with some electronic contact cleaner, if you haven't already. I have known of several cases on Mustangs, and my own Ranger, of this being the cause of a poor idle.

There are plenty of other things it could be, but this is a cheap and super easy thing to try.

Just remember not to touch the wires, they are fragile!!

OK. I'll keep that in mind. I'm replacing the fuel pump with the Walbro and a fuel filter. If that doesn't do it, I'll try your suggestion. However, I'll need some more guidance. I assume the wires are inside the throttle body and I remove the throttle body to do this? Where do I get electronic contact cleaner, Radio Shack? Thanks.

 

[sdpatt]

MichaelH:
Yes. When warm, it cranks a long time before catching, then it stumbles a bit. If I stop cranking and try again, it starts right up. That's what led me to my first suspicion of the CID, but I don't get any codes which would indicate the CID. So, you think the fuel pump is on it's last legs?

That symptom is an indicator of a leaking fuel pump discharge check valve. This is really just a ball bearing that plugs the outlet on the pump when the pump is not running. It prevents the fuel pressure in the fuel line from releasing to the tank. This requires that the pump spin for a couple of seconds to bring the fuel system up to the required pressure so that the engine can start and run normally. The only correction is to replace the pump. Realize though that this is not a driveablility problem and can be circumvented by turning the ignition key to ON for a couple of seconds to let the pump spin for about 1.5 seconds then turning the key to START.

The 211 code is a key failure indicator of the crankshaft position sensor (CPS) and tells you that you had better plan to replace this sensor soon. It is a small extra effort when changed during a timing belt service. Are you due for one soon?

After replacing the TPS, did you set the idle output voltage to less than one volt? You can search on this adjustment, but a simpler way without a voltmeter would be to loosen the scerws on the TPS and rotate it within the mounts a tiny amount in the CCW direction. You will then have to re-perform the idle speed reset .

 

[MichaelH]

sdpatt:

MichaelH:
Yes. When warm, it cranks a long time before catching, then it stumbles a bit. If I stop cranking and try again, it starts right up. That's what led me to my first suspicion of the CID, but I don't get any codes which would indicate the CID. So, you think the fuel pump is on it's last legs?

That symptom is an indicator of a leaking fuel pump discharge check valve. This is really just a ball bearing that plugs the outlet on the pump when the pump is not running. It prevents the fuel pressure in the fuel line from releasing to the tank. This requires that the pump spin for a couple of seconds to bring the fuel system up to the required pressure so that the engine can start and run normally. The only correction is to replace the pump. Realize though that this is not a driveablility problem and can be circumvented by turning the ignition key to ON for a couple of seconds to let the pump spin for about 1.5 seconds then turning the key to START.

The 211 code is a key failure indicator of the crankshaft position sensor (CPS) and tells you that you had better plan to replace this sensor soon. It is a small extra effort when changed during a timing belt service. Are you due for one soon?

After replacing the TPS, did you set the idle output voltage to less than one volt? You can search on this adjustment, but a simpler way without a voltmeter would be to loosen the scerws on the TPS and rotate it within the mounts a tiny amount in the CCW direction. You will then have to re-perform the idle speed reset .

Thank you. I'm replacing the pump (wanted a Walbro, anyway) and fuel filter. I'm having the CPS and water pump checked. The CPS and timing belt were replaced just 10K ago, so I'm hoping for a bad ground. I'd rather not have to do that again just yet, unless the experts do some more testing and confirm the worst. Then I'll have the CPS and water pump done.

 

[Electricat]

MichaelH:

Electricat:
You should try cleaning the MAF sensing wires with some electronic contact cleaner, if you haven't already. I have known of several cases on Mustangs, and my own Ranger, of this being the cause of a poor idle.

There are plenty of other things it could be, but this is a cheap and super easy thing to try.

Just remember not to touch the wires, they are fragile!!

OK. I'll keep that in mind. I'm replacing the fuel pump with the Walbro and a fuel filter. If that doesn't do it, I'll try your suggestion. However, I'll need some more guidance. I assume the wires are inside the throttle body and I remove the throttle body to do this? Where do I get electronic contact cleaner, Radio Shack? Thanks.

The metal tube just off your filter box is the MAF, the part between the filter box and the accordion-type tube that goes into the throttle body. Just undo the hose clamp on each end to take it out. Look through it, there is a large hole, and also a small hole, inside which you will see two small wires. Those are the sensing elements. They occassionally get dirty, or gunked with oily stuff if you have a K&N type filter. Just spray them down good with the cleaner. Like I said, it is unlikely that this is your problem, but it is an easy thing to try. YOu can get the cleaner at Radio Shack, or most any auto parts store. CRC is the brand I use. I like to keep some around for cleaning out grubby connectors, switches, etc.

 

[MichaelH]

Electricat:

MichaelH:

Electricat:
You should try cleaning the MAF sensing wires with some electronic contact cleaner, if you haven't already. I have known of several cases on Mustangs, and my own Ranger, of this being the cause of a poor idle.

There are plenty of other things it could be, but this is a cheap and super easy thing to try.

Just remember not to touch the wires, they are fragile!!

OK. I'll keep that in mind. I'm replacing the fuel pump with the Walbro and a fuel filter. If that doesn't do it, I'll try your suggestion. However, I'll need some more guidance. I assume the wires are inside the throttle body and I remove the throttle body to do this? Where do I get electronic contact cleaner, Radio Shack? Thanks.

The metal tube just off your filter box is the MAF, the part between the filter box and the accordion-type tube that goes into the throttle body. Just undo the hose clamp on each end to take it out. Look through it, there is a large hole, and also a small hole, inside which you will see two small wires. Those are the sensing elements. They occassionally get dirty, or gunked with oily stuff if you have a K&N type filter. Just spray them down good with the cleaner. Like I said, it is unlikely that this is your problem, but it is an easy thing to try. YOu can get the cleaner at Radio Shack, or most any auto parts store. CRC is the brand I use. I like to keep some around for cleaning out grubby connectors, switches, etc.

Sorry. I know where the MAF is.Wasn't thinking. Anyway, I'll do that as a last resort. Thanks for the tip on the CRC. BTW, I read an article on SHOTimes FAQ about cleaning the turn signal/ww stalk and they mentioned cleaning it out and putting some dielectric grease in there. I assume I can also get that at Radio Shack?

 

[MichaelH]

Here's an update on progress. Definitely running better, but not finished.
Ordered a Walbro fuel pump. It's not in, yet, but here's what I've done:
1. Replaced TPS
2. Replaced IAB/IAC
3. Replaced front O2 sensor
4. Replaced fuel filter
5. Cleared codes and performed Idle Reset
6. Cleaned throttle body
7. Had the water pump/CPS inspected - OK
8. Reran tests: KOEO, KOER - no codes!

I have only one more annoying issue, which I hope will go away when the fuel pump is installed (along with the long cranking when warm). I sometimes notice a slight hesitation when I give it throttle. Could this be low fuel pressure from the bad fuel pump? Or something else?