Hi-reving Reatta

[Bushwack]

A couple weeks back I posted a problem with my car (but can no longer find the thread). To recap, unless the car was complete warm (or after about 20 minutes of driving), the car would rev to in neutral to about 1500 RPM until I came to a complete stop. For example, can be going 35 MPH and then shift into neutral and the tach would hover around 1500 RPM until I came to a complete stop; at which time the revs would go down to a steady 750 RPM. Did a fuel injection services, IPC, new wires but still had the problem.

This morning I decided to see heed the advice I gave to someone else for a completely different problem. I disconnected battery for about an hour (after I had the car idle for a few minutes) then re-connect. Having done so, the car is behaving as it should (so far after 5 miles of city driving). Not sure what this means though. Did the ECM need a reset or do I have a bad ECM? Or is this an anomaly and I should leave things as is and move forward.

Just thought I'd share...

[Guest MercWagn]

First thing to do with high idle issues is to check the throttle position sensor voltage and connector.

[Bushwack]

First thing to do with high idle issues is to check the throttle position sensor voltage and connector.

That was done and its within specs. If it acts up again (and there are no vacuum leaks), it was suggested the last possible item that can be at fault is the coolant sensor; as the car only idled correctly once at full operating temperature.

I'm about to take it on an 8 miles round trip drive (after sitting for 2 1/2 hrs) and hoping all will be good.

[Bushwack]

Well...the problem came back. Revs high in neutral until the car reaches normal operating temperature.

Mechanic (at his expense) is replacing the thermostat and coolant (not temperature) sensor. Since I'm not paying for it, why not?! Mechanic thinks the sensor has gone bad and can only determine that by also replacing the thermostat.

[D-a-n-i-e-l]

when is the last time you replaced your O2? The coolant sensor is a more likely cause but The O2 can go bad in some odd ways. Also yo stated that the injectors where serviced. the cleaning agents used to do that service can damage the O2 also, weather they were removed or not.

[Guest Metricwrencher]

when is the last time you replaced your O2? The coolant sensor is a more likely cause but The O2 can go bad in some odd ways. Also yo stated that the injectors where serviced. the cleaning agents used to do that service can damage the O2 also, weather they were removed or not.

Aloha, Bro Daniel:

I use to live in Mililani Town on Kipapa Drive next to the Elementary School. What a great place to drive a Reatta, especially one with a supercharger. When I was there, if you had the right ID, you could still drive/ride over Kolekole Pass. I suspect that road is closed since 9/11 but the back roads through Kunia or over to Waialua would be a fine exercise for your hot-rodded coupe. Please keep us informed of the progress to upgrade your car.

Mahalo,

Don

[Bushwack]

when is the last time you replaced your O2? The coolant sensor is a more likely cause but The O2 can go bad in some odd ways. Also yo stated that the injectors where serviced. the cleaning agents used to do that service can damage the O2 also, weather they were removed or not.

Thanks Daniel for the advice

Here is where things stand:

Had the fuel injectors serviced (problem occurred before the service so I don't think it is the O2 sensor. Also don't have an O2 sensor error code on the ECM).

As I said previously, new TPS, new wires and as of this morning, new thermostat (engine does idle smoother when hot) and new coolant sensor. Still, problem not resolved. Going 15...20...35MPH then shifting into neutral, engine will idle at 1,500 RPM until the car comes to a complete stop. Then idle settles at 750RPM. This only occurs during the first (approx) 15 minutes from a cold start. Once at normal operating temperature, car runs great.

I went into the ECM and other than a 6552h code, it shows no error codes. I did get various "ED" readings (Ei, Eo and E codes) but the ED codes do not match what I see on Ronnie's site (ECM Diagnostic Codes - Reatta Owners Journal). I have codes such as ED01, 02, 11 and so on while these are not on the previously mentioned link.

Any suggestions??? Other than the fuel injection service & IPC, mechanic has been good - troubleshooting and thermostat & sensor has been at his expense. But I'd rather find the problem and not throw items underneath the kitchen sink at the car.

Edited October 16, 2012 by Bushwack
Blue indicates typo correction (see edit history)

[Guest Mc_Reatta]

What is the ambient outside temperature when your car is doing this?

What does the MAT sensor say it is? (ED23)

[Bushwack]

Problem has occurred early morning before sunrise (65 degrees) and today (90 degrees).

The ED23 reading is at 45.

[Guest MercWagn]

I am not certain about these engines specifically, though I know series II engines (with their plastic intakes) have intake/gasket problems, but it sounds like an expansion-contraction issue: engine comes up to temp and there is expansion--idles better; when cold/contraction--idles improperly. I wonder if your intake gasket has failed, causing problems. Also, if I remember correctly, re-torquing the throttle body fasteners is on a regular maintenance schedule (throttle body gasket failure is possible also).

Thinking out loud here, based on my experience with carburetor-equipped vehicles, have you "read" the spark plugs, looking for a lean condition in a cylinder (I'm uncertain if O2 sensor data would give an indication of this). If there is an internal vacuum leak, due to gasket failure, would it not provide an indication on the spark plug? Just something to consider.

Just throwing these ideas out there, since there are so many things that could be occurring to cause this.

[Bushwack]

I am not certain about these engines specifically, though I know series II engines (with their plastic intakes) have intake/gasket problems, but it sounds like an expansion-contraction issue: engine comes up to temp and there is expansion--idles better; when cold/contraction--idles improperly. I wonder if your intake gasket has failed, causing problems. Also, if I remember correctly, re-torquing the throttle body fasteners is on a regular maintenance schedule (throttle body gasket failure is possible also).

Thinking out loud here, based on my experience with carburetor-equipped vehicles, have you "read" the spark plugs, looking for a lean condition in a cylinder (I'm uncertain if O2 sensor data would give an indication of this). If there is an internal vacuum leak, due to gasket failure, would it not provide an indication on the spark plug? Just something to consider.

Just throwing these ideas out there, since there are so many things that could be occurring to cause this.

Appreciate the advice. The plugs were replaced last May (this hi-revving issue started about a month ago).

The intake gasket was ruled out when the mechanic checked for vacuum leaks.

I'm wondering whether its wise to clear all codes (not that I had a code appear) then re-check the ECM after the car has been idling for no more then 5 minutes from a cold start. Makes any sense???

[Guest Mc_Reatta]

If you are leaning away from a thermo-mechanical problem, have you tried determining if the situation can be confined to an open loop only issue.

As soon as you start the car enter diagnostics and enter ECM mode. The ECCP will now display the status of various ECM functions. The fan speed lights will show two important important parameters. The "HIGH" speed indicator will be off while the engine is in open loop. When the ECM confirms the engine and O2 sensors are hot enough, it will switch to closed loop and the high fan speed light will come on.

Does your idle speed problem go away when the engine enters closed loop or sometime after the light comes on?

When the high speed fan light comes on (closed loop), is the fan LOW speed light cycling on and off regularly. This light signals the state of the O2 sensor. On indicates rich and off shows lean. Should cycle back and forth. If it is on or off more than the other way, may indicate O2 sensor isn't fully warmed up yet or weak.

If the idle speed issue does not go away when the closed loop light comes on (High fan speed) but improves a little later, does the LOW speed light tend to stay either on or off longer, and the when the idle straightens out does it cycle more regularly?

Hard to troubleshoot all the variables involved unless we can narrow down what the ECM is seeing and considering while the problem is occurring.

[Bushwack]

If you are leaning away from a thermo-mechanical problem, have you tried determining if the situation can be confined to an open loop only issue.

As soon as you start the car enter diagnostics and enter ECM mode. The ECCP will now display the status of various ECM functions. The fan speed lights will show two important important parameters. The "HIGH" speed indicator will be off while the engine is in open loop. When the ECM confirms the engine and O2 sensors are hot enough, it will switch to closed loop and the high fan speed light will come on.

Does your idle speed problem go away when the engine enters closed loop or sometime after the light comes on?

When the high speed fan light comes on (closed loop), is the fan LOW speed light cycling on and off regularly. This light signals the state of the O2 sensor. On indicates rich and off shows lean. Should cycle back and forth. If it is on or off more than the other way, may indicate O2 sensor isn't fully warmed up yet or weak.

If the idle speed issue does not go away when the closed loop light comes on (High fan speed) but improves a little later, does the LOW speed light tend to stay either on or off longer, and the when the idle straightens out does it cycle more regularly?

Hard to troubleshoot all the variables involved unless we can narrow down what the ECM is seeing and considering while the problem is occurring.

I was going to tackle this over the weekend but I'm eager to get to a resolution.

With the car running and in ECM diagnostics mode (and the car's temp at 145*), the HIGH indicator was off and the LOW remained on. It wasn't until engine temp read 176* did the HIGH come/stay on and the LOW started to flash intermittently. My high revving problem still existed.

About three minutes after the car's temp reached 195*, the high-revving went away. During that time, the three snapshots below of the ECC had these reading when under various accelerations (don't know what they mean). Once at idle, only the HIGH stayed on and the LOW flashed on and off (at an inconsistent slow pace). Under acceleration and with the high-revving gone, the LOW indicator flashes on and off with near regularity.

As I pulled into my garage, I did hear the second fan on while the car remained a consistent 195*. Two thoughts I had was could the problem be related to the 2nd fan being on (is there a relay I can change out for the 2nd fan or just take the relay out temporarily w/o do harm?) and on a far reaching idea, could the fuse (or relay) for the cruise control be the problem (cruise control was always off - never used).

Thanks.

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[Ronnie]

I haven't tried kicking into neutral at 30 mph to see how the car idles but reading about it brings questions to mind that I would like to throw out.

Could the high idle speed while slowing down be a normal function of the ECM to reduce emissions until the engine has reached normal operating temperatures? Have you tried the same thing on another Reatta to see if it idles high at 30 mph in neutral as well?

[Bushwack]

I haven't tried kicking into neutral at 30 mph to see how the car idles but reading about it brings questions to mind that I would like to throw out.

Could the high idle speed while slowing down be a normal function of the ECM to reduce emissions until the engine has reached normal operating temperatures? Have you tried the same thing on another Reatta to see if it idles high at 30 mph in neutral as well?

Thanks Ronnie - I didn't thoroughly test out the other Reatta but I know it doesn't have a problem (drove it a couple days ago). I can tell right off as when I'm braking, I'm not fighting the car to stop (as if one foot is slightly on the accelerator at the same time). That's how I first noticed the problem. After the car warming up for a couple minutes, when I put it into gear and was approaching a stop sign, I had to make considerable effort to stop the car as it felt it was accelerating (which it is at 1,500 RPM).

Now....Since the idle drops to 750 at a complete stop, is there a sensor (or other device) that measures air flow (or air resistance) while the car is in motion?

[Ronnie]

Now....Since the idle drops to 750 at a complete stop, is there a sensor (or other device) that measures air flow (or air resistance) while the car is in motion?

Nothing that I know of that measures air flow across the car... if that is what you're asking. The MAF sensor measures air flow into the engine. The Vehicle Speed Sensor (VSS) sends a signal to the computer to tell it the car is in motion. I'm sure that signal is used for more than just displaying the speed on the dash but off the top of my head I don't know what it would be besides torque converter lockup.

[harry yarnell]

Check the PCV gromet in the intake on the passengers side. They get hard, brittle, and fall apart, causing a nasty vaccuum leak....and high idle.

[Bushwack]

Check the PCV gromet in the intake on the passengers side. They get hard, brittle, and fall apart, causing a nasty vaccuum leak....and high idle.

Thanks Harry. But if there was a vacuum leak, wouldn't the hi revs always occur?

I took the car on an errand today. As expected, after about 15 minutes the problem went away. I reached my destination, turned off the car and returned no more then 3 minutes later. Turned on the ignition, went into drive and noticed as I was heading to a stop sign the hi revs came back. This occurred for 2-3 more city blocks until it went away. So now, even with the car having been driven for 40 minutes, turn it off and on within minutes and the problem briefly comes back. So maybe the focus is a starter issue or a faulty (oxygen) sensor? Ronnie mentioned a VSS (Vehicle Speed Sensor) but I couldn't find mention of it in the FSM.

I'm reaching as there is no error code and have already replaced the 'usual suspects'.

[Guest Mc_Reatta]

This latest revelation has me tilted enough towards the O2 sensor to recommend that you change it out. I can't think of anything else under the hood that would cool enough during a 15 minute rest to revert to a cold running condition. Most items under the hood would actually get hotter when the airflow and coolant circulation is stopped.

Replacing the O2 sensor is such an inexpensive, routine undertaking that it doesn't make much sense to continue troubleshooting this problem without eliminating it as a cause. Make sure you chose a reliable replacement, and if you haven't changed your plugs in recent memory, it would be wise to replace them and maybe also the wires at the same time as getting to cylinders 4 and 6 is much easier with the O2 sensor out of the way.

[wws944]

So the problem remains when the system switches from open loop to closed loop (i.e., when the HIGH light turns on)...

At risk of not going back and looking at your last thread, have you checked out the IAC (idle air controller) yet? Did your mechanic clean up or replace the IAC when he did the throttle body? You can watch the ECM try to command the IAC by monitoring ED22.

The one time I have seen something similar with mine was when I was looking for the cause of a different idle problem three years ago. I unplugged the IAC and got exactly the same symptoms you describe - with the high rpm. Though I didn't try driving it around that way. Plugged the connector back in and the idle went back to, more or less, normal idle

It is just two screws and a connector to remove the IAC and clean it up. (Be sure to put a rag under it to catch the screws you are sure to drop...) From Ronnies site:

IAC Cleaning Instructions - Reatta Owners Journal

I hope there isn't some sort of intermittent connection in the wiring to the IAC...