EGR Code 51--94 Sidekick 16 valve

[bruce3404]

I've been getting this code sporadically over the last few thousand miles. I can reset the Check Engine switch after erasing the code by dis-connecting the battery, but eventually the check engine light will come back on. I read the recent post entitled "EGR Flow Problem", but it applies to a '96 and I don't think my system is the same. I have an EGR Modulator which has three hose connections:
1. To the back of the EGR valve (on the metal disk behind the diaphragm).
2. From the bottom of the modulator, straight down to a housing in front of the EGR diagphragm, which I think is part of the EGR valve.
3. To a switch just above the charcoal cannister. This particular connection starts with a hose, which then connects to an extremely thin piece of tubing (maybe 1/8" diameter) which curves around the left side of the intake manifold before it connects to the switch above the charcoal cannister. From that same switch is another spaghetti thin tube which also wraps around the intake before it re-enters the intake a few feet above the air filter assy.

The EGR valve appears to be working properly. What else should I be looking at to resolve this problem?

[cheyenne'88]

How did you check to see that the egr appears to be working properly?
It should be checked at both cold and normal temps, by revving the engine while you feel for movement in the valve. (cold-no movement is good, warm-movement is good)
Your system is the same as all '86-98 egr's, unless you're in CA. You have a valve and a modulator.
The Haynes book has some tests for the modulator as well. (The books sell for around $16.) The procedures are pretty simple.
1st test: plug one of the vacuum ports on the side of modulator and blow in the other, and the air should come out the filter at the top of the valve.
2nd test: connect a vacuum pump to a port on the side of the modulator, plug the other side with your finger, and blow in the port on the bottom... operate the pump; the modulator should hold vacuum as long as air is being blown into the bottom port.
Also probably want to check/replace vacuum hoses to and from egr system.

[Suzuki01]

I guess it pays off having a TECH 2 sitting in my garage...hehe Just hook that shit up to the car and look it up in the books.

[Tinker]

Well a gobbledegook super scantool II may be great, but the code 51 is a code ONLY used on CA models and it is generated by a thermal sensor on the egr itself. All it does is verify gas flow. Mine is cooked. Only Ca models have this sensor, and all it does is trip the light if it doesn't detect heat. At least it makes you fail smog tho... Oh, and it is on the top of the diaphragm on the side of the head. Looks kinda like a small 02 sensor.

[bruce3404]

Thanks for the further update, Tinker. I still haven't resolved the problem...would you mind sending me a photo of the specific part I need to replace? I purchased my Sidekick in WA and am surprised that it has a CA emission system.
bruce3404@hotmail.com

[jtgh]

tinker
can you tell me what year has this thermal sensor?
i want to look it up. curious.
I am interested in all EGR monitor methods.
I know I have not seen them all.
some borderline on magic.
bruce:
your 16valve has an EGR pipe that can close down with carbon.
not to mention both ends of pipe at its juncture. Common.


Each car co. thinks up wild ways of doing it. the EGR MONITOR test.
OXY profile, MAP profile , Switches, pots in EGR,termistors in EGR.
makes head spin.

looking at my parts list i see no electrical connections (89-98) at EGR except on 98 1.8liter, see conn on end of egr ?

where is it?
some cars with out MAF can do it this way. (8 valve this era)
they are just reading the AIR TEMP sensor rise?

but this 1.6 L 16v has a maf and the Air temp sensor is in the MAF.

( EGR FAILS )
FSM shows how to test each part. Suck on diaphrams nipples or use mityvac tool.
then clean EGR valve.
also any vacuum leak can cause it. (fools OXY and MAP method of EGR monitor).

ON these dumb ECU's it just means something is wrong.
The EGR can be perfect and fail because:
possible besides EGR parts:
this year:94 16V
Vacuum leak ( but engine will race hot, if no race see next)
Oxygen sensor is bad. (if over 60k replace it)
IAT air sensor on intake manifold is bad. (water and Air next to each other)
Map sensor is bad. make sure the tiny filter on the line is clear.
Clean MAF sensor , maybe its coked up and causing rich condition.
rich maysome how fool the EGR monitor.

Please remember this Monitor is very stupid. Take the EGR Flow with a grain of salt.

[jtgh]

best for last: right here on this forum.
http://www.suzuki-forums.com/suzuki-...highlight=fail

This 95 engine 16v , I am told , uses the MAP drop method.
eg:
ecu commands EGR open.
ecu looks a map , and looks for pressure drop ( less vacuum).
caused by exhaust invading the intake plenum.
if the drop doesnt happen, code 51 sets,.
Code 51 says you have a gross failure to detect that EGR action.
I says Exhaust gases are not entering the Intake , enough.
(clogged passages, bad solenoid valve, egr valve, lines or bad MAP sensor)
when code 51 also sets the engine managment to go to low ignition advance and or rich.
called back up strategy. Poor Gas mileage results every time.
This is to prevent pinging or detonation. very bad to have that.

it is just a go /no go test.
later Kicks 96+ on can calculate flow rates (OBD2 system monitors)
on newer cars its a code P0400.

also on the 96+ we have:
The Manifold Differential Pressure (MDP) sensor and the EGR Bypass (EGR valve (mounted in the vacuum line between the EGR modulator and the EGR valve.) The ECM uses these components to compare the pressure in the EGR system with the pressure in the intake manifold to check for a blockage."
look for these parts, California cars.

back to 1994 EGR:
DTC 51?
Can you push in on the EGR diaphram while the engine is idling and
the engine stalls? ( or very close, it will stumble and die)
IT MUST DO THAT !!!
Also you can attach a hose to the EGR vac port and
suck on it and get the same results. "MityVac time"
This will tell us all of the EGR passages are clear and working
if you car starts and runs with the EGR valve removed , your passages are in fact clogged and the ECU is not Lying.
Inspect ever inch of the EGR path Exh to and Inside Intake EGR passage.
I think this is 99 percentile failure mode.

[jtgh]

It is amazing how popular the code 51 error is on this forum.
This may help:
only these cars have 51 checks:
90-93 cal cars only
94 on , Fed and Cal Cars have 51 checks.
But in 96.5 cars on they became OBD2 cars and the code changes to
P0400 , and even more difficult to clear.

This may help , for these older cars:

EGR

I made this during some midnight insomnia.

[1.6_Sami]

Originally Posted by jtgh

tinker
can you tell me what year has this thermal sensor?
i want to look it up. curious.
I am interested in all EGR monitor methods.
I know I have not seen them all.
some borderline on magic.
bruce:
your 16valve has an EGR pipe that can close down with carbon.
not to mention both ends of pipe at its juncture. Common.

Ok, I have the same issue with my 94 1.6, I have cleaned out the tunnel into the intake, egr stumbles the engine when vacuum is applied, tested modulator. The only thing I cant find help with is testing the sensor that screws into the egr valve. How do I test this, is there an easy way and what is this part called? I can reset by disconnecting the battery but after about 3 hours of driving my error 51 and engine light comes on. The funny thing is that I just past smog. I disconnected the battery to reset code and took it in the shop. They went through all the testing and it past.

Thanks in advance.

[jtgh]

wierd i posted the full data on that yester day.

its on my egr page.

the control+F , search Probe. the tests are there.

most EGR fails are cloggs.
but my last one was a coil on the VSV that finally stayed open.

got you ! you lil bugger......

lets work it out;

is your CATCON still on car and not blowout, rodded out or missing.
does it have factory stock back pressure.

it is manditory that it does or the EGR mod valve becomes useless.