EGR ?

[Lon]

93 KICK , 1.6L 16V 5speed Thorley header

Fuel pressure , timing cam timing sensors check ok per FSM plus new caps in ECU

Problem:
slight dead spot right off of idle , and missing when trying to "PUTT" at 1,500 to 2,000 RPM.

What I found:
I plugged the vacuum line BEFORE the EGR modulator ... runs perfect.
hook line back up , plug EGR vacuum line AFTER the EGR modulator ...
runs perfect.
Hook EGR back into system , flat spot and miss return.

Question:
Should the EGR have an effect on the engine at this low of rpm?
Is the modulator or the temp sensor allowing the EGR to open too soon?
If the EGR is not hook up , will the EGR temperature sensor "LIE" to the ECU because it is not getting hot enough.

Thanks ( I hope)
Lon

[fixkick]

very very nice checking there.
the EGR modulator is tuned to use the cat back pressure.

The egr is dead, at 0 miles per hour, totally. and at W.0.T.
so this must be driving . when cat back pressure , is strong, and stronger up hills.
yes, the modulator works backwards from what wed expect. its is a very very odd device.
the key to this is my cross section drawing.
if the cat is missing, there is no putt, or is crazy week.
the modulator diaphragm moves in a backwards way.
no the thermoprobe is only a test, and code 51.
the thermoproble can be fooled, a 10k ohm resistor (in its place) lies to the ECU, the silly ECU forgets to check for cold then hot, (at cruise) then assumes it was cold before, and is hot now, its dumb that way, it just waits for the EGR to go active (say light cruise) and if hot is read, no CODE 51 are tripped. It fails to do a real transition tests. (all this is theory we'd never run a 10k on the street, but do all day in South America. )
yes the dead thermo probe "EGRT", stuck cold does set 51s, (correct ECM in place)

Data Points for the EGRT: source Pg, 6E99 FSM. ( has a graph plot and test procedure)
212

[Lon]

First off , Thanks for the reply.
I have only had the car for 7 weeks. Have been trying to fix the 1,500 to 3,000 RPM NO LOAD "surge or gallop" as discussed on my previous posts.

What I have learned:
car has two (2) catalytic converters ,my guess is, trying to get it to pass smog ( previous owner).
The exhaust pressure tube that runs from the EGR valve to the modulator was the wrong type of tube and was swollen and not sending a good pressure pulse to the modulator. Changed the hose , no load surge is gone , but now it has the low RPM miss .Maybe too much back pressure (due to 2 cats) is opening the EGR too soon. Also discussed in previous post , my modulator does not have the "orifice" at the "P" fitting as shown in the diagram you posted. Also I can put a .068 diameter gage pin all the way through both "P" and "Q" on my modulator,My friends modulator only has a .35 hole through it.
My "vent hole" is clear and modulator works per FSM tests.
Does the EGR thermo sensor tell the ECU to turn on the EGR solenoid?
Thank you again
Lon

[fixkick]

wow 2 cats, that cant be good for back pressure. never seen that, the stock cat is TWC three way cat.
2 cats, well the first runs right hot, but #2 runs dead cold (cat actions) so acts as just a screen filter huge and collects carbon and packs up, 2 cats is a very bad idea.


no orifice. is normal.
is the modulator p/n on top correct?
no, the thermo-sensor is only a sensor and is not in control of egr in any way, its only for the monitor, (pass /fail 51) nothing more.
ill look up yo pn now. these modulators back in 1993 are on many cars, toyota's and might be wrong one.
the modulator sets the flow based on back pressure, more exh pressure more flow.
ill pull up the pn from the EPC now.

suz pn, 18112-55A00 ( Changed in 1995 at a spec. vin S6400243 , to dash 60B00)
on the top is DENSO (nippon denso)
the odd thing is all engines 8/16 used 60B mode
then in 92 to 95 (early) all 16used, 55A. only the 16v did and only 3.5 years. ,very odd.

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NICE discovery that bad PUTT tube. must be collapsing. (seen many turn to mush, looks like kids playdoe clay, my joke is turning back in the Dinosaur guts.
it it is missing, there is no EGR action, so it must be too much back pressure.

it's a silly Rub Goldberg setup, the newer 2.0L uses engine calculated load (very accurate ) then open the EGR motor. on even newer cars it reads back how far open.
the back pressure method is really a pain for cars on smog tests.
can be a private horror.

here is 96

[Lon]

Denso 18112-60B00. same number is on my friends 93 Kick 1.6 16V with AUTO transmission

I am going to run it with the EGR vacuum line blocked off until I can get the exhaust system straightened out.
thanks again
Lon

[fixkick]

my wild guess at the other cars, Denso valve. orifice
is for larger engines that may need this for keeping the vacuum more steady. and not bounce.
the flow. looks like this.

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i dont blame you, its real pain to tune this ,
for me like a monkey playing Violin.

if the back pressure is too much, the horz axis above shifts right.

good luck to you.

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stuff steel wool in the putt tube and hope it slows the putt putt down>?