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5 Posts
Discussion Starter · #1 ·
I have a 1998 Acura 3.2 TL
I got a CIL code for a blocked EGR. So, following the guide I found on one of the Acura forums I took off the manifold and completely cleaned it along with the EGR tube.

I put everything back together using new gaskets.

Now the engine doesn't run smoothly at start up and the RPMs bounce up and down and it may even shut off.
If I rev the engine a bit until it's warmer, the idle settles down and stays at about 600-700 (right between the 1k and 500 lines)

If I rev the engine at this point, at about 2500 rpm, the engine starts to run more roughly. But not that bad.
However, as soon as it hits 4k RPM, it drops back immediately to 3k RPM.
If I try to keep it at 4k rpm, the RPMs just keep bouncing between 3k and 4k rpm.

After I ran into this problem, I went ahead and put 1/3 can of Sea Foam into the PCV, gas, and oil.
There was a lot of smoke at first but that's cleared out. But it didn't seem to make a difference.

The code I'm getting is p0505.
I took the throttle body back off and cleaned it some more, making sure all passages were clear.
I also took off the IAC valve and cleaned that out as best I could with carburetor cleaner.

So to sum up. I can't go over 4k rpm without it bouncing back and forth from 3k to 4k.
The engine runs a bit rough and the idle bounces around a little bit until the engine warms up.

Any suggestions?

7 Posts
Hope it helps

May I suggest..

P0505 - Idle Control System MalfunctionP0505 - Idle Control System Malfunction Here is some explanations about P0505 Idle control prob

The diagnostic procedure for the code P0505 usually includes inspecting the idle air control system components, checking the IAC valve power supply voltage, inspecting electrical connectors and wiring, as well as testing the idle air control system with a scan tool.
Sometimes the carbon deposits in the idle air control valve can cause it to be stuck open or closed. Sometimes even low coolant level can cause the idle fluctuation and the code P0505. Problems with the EGR and EVAP systems also can cause the code P0505
the stuck open idle air control (IAC) valve or broken power steering pressure switch wire can cause the idle to fluctuate, with the code P0505. As a solution Honda recommends replacing the IAC valve or (and) repair the power steering pressure switch wire located right above the steering rack boot on the passenger side of the vehicle.
It may also help
P0500 Vehicle Speed Sensor (VSS) Circuit Malfunction
P0501 Vehicle Speed Sensor (VSS) Range/Peformance Problem
P0505 Idle Control System Malfunction
P0506 Idle Control System RPM Lower Than Expected
P0507 Idle Control System RPM Higher Than Expected
P0511 Idle Air Control (IAC) Valve Circuit Malfunction

like on Honda, it may be a valve prob
Or It could be a low battery
Or the ignition coils (.. leading to a missfire).

(1) P0505 - Symptoms first - Fluctuating idle once car was warmed up. Plus Hi idle around 1500. Occassional bucking while driving at slow speeds and rpms under 2000.

Things I found and checked - IACV resistance checks and mechancial were good. TPS voltages and resistances were good. Checked for vacuum leaks, didn't find any. ECT Sensor resistance verified once car was warmed up.

In the end this is what I did, bought a complete throttle body from the junkyard. Built one IACV out of the original and used one. Even though they both tested the same and were mechanically the same. And sprayed the crap out of both the IACV and every port of the throttle body with throttle body cleaner. I believe my problem was just dirt or carbon build up. So I would ensure everything is very clean prior to running out for parts.
Hope it helps!

Edit :

*I have also 1997 3.2 TL

5 Posts
Discussion Starter · #4 ·

Ok, in the spirit of this cartoon: xkcd dot com/979/ (make sure you hover your mouse over the picture to see the Alt text), this is for the people in the future who might find this post.

This is on a 1998 Acura 3.2 TL
Everything is fixed and working. Here's what I found out and did.

This all started with with a DTC P0401 Insufficient EGR flow.
I followed these guides to clean it out. Holy crap that was a lot of gunk!
www dot acuraworld dot com/forums/f40/diy-egr-intake-manifold-cleaning-68465
www dot acura-legend dot com /vbulletin/f13/diy-egr-removal-pics-68912/

I got everything cleaned out and put back together with new gaskets.
Got the gaskets here. About half the price of my local dealer.
www dot acuraoemparts dot com/delray/jsp/home.jsp

I started the car and the idle was not happy but it was more or less fine after the car got up to operating temp.
However, I was unable to get the engine over 4000 rpms. It would hit 4k then cut out until it dropped down to 3000 rpms. It would then bounce back and forth between 3k and 4k.

I was also getting another code(s).
On one of the Acura forums I found that you could read the DTC code by shorting the service connector underneath the glove box and the light would flash. A long blink for the 10 digit and a short flash for the 1 digit.
This is incorrect and led me to think I had code p0505 (5 short flashes pause 5 short flashes).

After messing around with the IAC valve, I finally took it to O'Reilly's to borrow their code reader.

The engine was still cold when I got there and the code I got was P0113, Intake Air Temperature Circuit High Input. This sensor is on the top of the main manifold chamber just behind and to the right (driver's side) of the throttle body. Attached with two Phillips head bolts.

I took the negative cable off the battery to clear the codes and tried again.
This time the car was up to temperature and I didn't get P0113 anymore, instead I got P0106 which is the Manifold Absolute Pressure Circuit.

According to the '96-'97 3.2 supp service manual (pg 11-57), the first step is to see if there's any vacuum leak between the MAP sensor and the Throttle Body.
That's great but for the life of me I couldn't figure out where this sensor was. I searched this forum and others and Googled to no avail.

As it turns out, the sensor is not directly connected to the Throttle body. Instead it's connected by a rubber vacuum hose to a metal pipe. The actual sensor is in the control box that's bolted to the firewall on the passenger side and is connected to the Throttle Body by vacuum hose number 21.

Later I found a diagram of the Control Box on page 11-9 of the '95-'98 2.5 TL Service Manual which shows the MAP sensor.

When I finally found it, I realized what the problem was. When I removed the 21 vacuum hose from the throttle body, I tore it so I replaced it with new hose.
Unfortunately, it turns out it wasn't as nearly a tight enough fit and was letting air in.

I replaced the hose and for good measure I took off the IAT Sensor and cleaned it.

The car started up, no codes and everything acted normally.

Now I just need a/c and a new windshield and she'll be good as new.

I hope this helps someone else.

10 Posts
I did the exact same thing, this past weekend. I was amazed at how accurate the step by step instructions were. However I am getting a different code P0117 the Engine Coolant Temperature sensor 1. This rascal is located right behind the intake hose going from the radiator to the water passage that's nestled between the throttle body and the manifold, and in front of the drivers side fuel rail. Other than unplugging it I did not mess with this sensor... any ideas on this?

5 Posts
Discussion Starter · #7 ·
I assume you are talking about the 2000 RL?

According to my 3.2 TL service manual, that code is either a short in the ect circuit, bad ECT sensor or bad PCM.
Sometimes just moving something in an old car can bring about other problems.

I haven't had to mess with the ECT so far so these are just educated guess.

Maybe there's some air in the coolant causing it not to read properly.

You could try taking out the sensor and cleaning it. That's what fixed my Air Intake sensor. I had left it in the manifold when I cleaned everything.

Try a known good sensor.

Other than that you need to find out if there's a short in the circuit.

Still, my best guess is making sure the connections are tight. Make sure there's no bubbles in the coolant. Take out the sensor and clean it.

Good luck.

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