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Modulator valve color codes - 1988 Ford F 250

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The Exhaust Gas Recirculation valve does just what the name implies: it diverts some exhau st gases back into the intake system at low engine speeds. This lowers combustion temperature to reduce NOx levels. It also reduces throttle response and bottom-end power.
Disabling the EGR valve is easy. Locate the valve and the EGR vacuum modulator valve (two gold-colored metal stampings, usually at the rear of the engine). The EGR valve has steel lines leading to it from the exhaust manifold. The EGR vacuum modulator has two vacuum lines between it and the intake manifold and a third vacuum (soft) line between the modulator and the EGR valve itself.
EGR Vacuum Modulator
EGR valve (arrow) is shown adjacent tosimilar EGR vacuum modulator valve. EGR valve is connected to exhaust manifold with steel lines. Modulator has vacuum lines only.
Disconnect the vacuum line between the valve and modulator and place any solid object of appropriate size (dowel, etc.) in the line, then reconnect the line. Or you can get a EGR block off plate

Oct 14, 2013 | Cars & Trucks

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Dodge 45 RFE transmission shifting hard only from 2-3 with no DTC's

Almost everything in a automatic transmission used to operated by the fluid flow. Nowadays transmissions have electrical parts too. I'm inclined to agree with your solenoid valve diagnosis. Did you notice any metallic debris in the bottom of the pan when you changed fluid?
If there is debris (and there almost always is) some may be in the bottom of the pan and some may be in the valve assembly. Hard acceleration means more fluid pressure and more fluid flow. Which may help the valve to operate. Some valves only operate a pilot circuit and ball check valve that further controls the major fluid flow.
Do you see any fluid around the modulator? And is the modulator port & orifice clear. Next time you have the pan off, see if you can pull the modulator and look at the mounting port and the orifice inside the modulator itself. If there is a dark colored square or rectangle in the pan. Wipe it off with a finger and check for grit or metal.

Jul 10, 2012 | Cars & Trucks

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How do you install a vacuum modulator in a 94 regal

Remove the vacuum line at the modulator. Remove the bolt and the modulator assembly retainer. Remove the modulator assembly. Reverse order to install.

NOTE: if the modulator valve comes out of the bore when removing the modulator vacuum assembly, note the orientation of the valve and reinstall it in the bore before installing the new vacuum modulator assembly. (see picture)


Aug 13, 2011 | 1994 Buick Regal Gran Sport

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The transmission won't shift out of 3rd and will only go up to 50 mph at around 3500 rpm.

check for a bad vacum to the modulator valve on your transmission,or a bad vacum to the modulator valve on the transmission. the modulator valve to the trans. works off of vacum from the engine,look for loose or disconnected vacum lines around the carb. or the air induction system. look for cracked vacum lines that seem to be sucking air when engine running at idle speed. in park. the modulator valve [usually] located on the drivers side,of the transmission,is the main cause of shifting failure. if the valve itself is bad, it will need replacement. thank you for choosing!

Mar 08, 2011 | 1996 Chevrolet Blazer

1 Answer

1995 Saturn automatic trans. shifting hard enough to brake motor mounts. Any suggestions for fixing

you may need to change the modulator valve on transmission and also check the modulator valve to be sure it's getting the proper vacum to it. the modulator valve controls shifting in the transmission. also suggest lucas transmission treatment be added to transmission fluid, it frees up stuck valves in transmission. hope this helps!!!

Sep 11, 2010 | 1995 Saturn Sl

1 Answer

Shifting problem,does not shift to drive

the modulator valve on the transmission may have gone bad, does it slip while driving or just simply won't shift easily? if you have to shift it manually from 1st to2nd to drive and it does fine it is a bad modulator valve on transmission or bad vacum to the modulator valve. hope this helps!!

Aug 22, 2010 | 1995 Isuzu Trooper

2 Answers

1999 toyota RV4 code P0401 EGR is good ,   vacuum line is good , what parts could be check.

It means that the egr valve is working, the problem is a very common one, it's the egr modulator valve and to some extent the vacuum switching valve(VSV) for the egr valve, the modulator is attached to the egr valve, remove it and if air can pass from the bottom port through it is defective, in that case replace it and see if it takes care of the problem, if the valve is ok the egr
vsv should be replaced.

Feb 13, 2010 | 1999 Toyota RAV4

1 Answer

Transmission will not change out of first. Can it be the modulator valve?

There is no modulator on your car. You need to scan the computer, there will be a code. Possible problem is a shift solenoid , output speed sensor, or park neutral switch. Worst case internal tramsmission failure.

Jun 27, 2009 | 1997 Pontiac Bonneville

1 Answer

Cant find modulator valve on 94 isuzu rodeo

if u mean the vacuum modulator valve, it doesn't have one, it is an electronically controlled transmission, what is the problem with trans?

Feb 19, 2009 | 1994 Isuzu Rodeo

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