EGR Cruise Test failure

[jingusflob]

Please Help!

I have a 1988.5 Samurai with a 1995 Sidekick 16v 1.6 MPI conversion. It runs almost fantastic. I have had almost no problems after a year of chasing all the ghosts out. I recently did a rebuild with new pistons, a new head and new cam. I've changed almost all of the sensors over time as I've had several problems with them in one form or another (bad idle,hard starts, high idle, misfires, etc). Much of the problems I've had I have been able to solve. There is only one remaining problem I am simply unable to figure out.

When I first start my vehicle it warms up as it should. 2,000 rpm for a couple mins, 1500 for a couple more, then it drops to 800 steady after about 5 mins total. I usually let it warm up this way then I get going. After I leave my neighborhood I'll drive for about a mile or two down the road at about 50-55 mph and that's when the problem starts. I usually get a CEL for code 51 while just cruising along steady. I've discovered when this happens, I can slow down to about 40 mph and 2,500 rpms and cruise for about a half mile to a mile and it will go out on its own.
Then it pretty much stays out the rest of the day and does not come back on. I simply cannot figure out why this is happening. I thought it was temperature related. So I changed the coolant temp sensor and thermostat. still doing the same thing.

Here's the list of things I've done in an attempt to solve this problem:

New EGR valve
New VSV
New Modulator
New MAF
New IAT
New ECT Sensor
New Thermostat
New ISC
New IAC
New PCM
New TPS
Cleaned all EGR ports in intake and head
Checked all vacuum lines to ensure no leaks
Timing is set perfectly at 800
New plugs
New wires
New cap and rotor
New fuel pressure regulator
New PCV
New Coil
Cleaned throttle body and its EGR ports

I've done stall test - it passes.
I've done live test - it passes.
I've done all the tests you posted on your page for all the EGR related sensors - they all passed.

The only thing I have not changed is the EGRT sensor. I did a test on it following the info on your fixkick pages. It seems to be putting out the correct resistance when checked at room temp and when I put it in boiling water. So I have not changed it. The cheapest ones I can find at $180 on line. I checked it to ensure the wires were not loose. I've checked the connectors and they are okay too. I cannot find anything wrong with it. So I have not wasted money on it yet.

I am now at the point where I just ordered a 4.7K and 10K resistors from radio shack. My plan is to put them in the EGRT connector one at a time and see if they make a difference. I suspect the ECM is not seeing the correct resistance at the correct time when it checks for the signal during cruise. I am not sure - I am just guessing.

Is there anything else I may be missing? It seems like it only does it when I first start driving it for the day. Then it resets itself if I slow down and cruise at 40 and 2,500 rpm for a minute or two. Its driving me crazy.

Any advice you can offer would be much appreciated. I am frustrated that I cannot figure this out and I've thrown so much money at it that I am near broke.

Thanks - JT

[fixkick]

so simple the EGR test fails.
1995 MPI
what ECU is there. that dictates what EGR you have
is car a USA car.
one is Calif
one is FEDeral USA>
one uses EGR thermoprobe to test EGR
other FED uses vacuum readings to test EGR.
did you read my EGRT page, on ohms tests.

here is what happens if EGR is missing you get DTC error 53, do you, missing, that shows its calif ecu, the ECU PN tell us if it is.
then what happens if all is right ECU/harness/egrt is correct
the car engine is hot
the car moves and then the EGR valve opens (if cat is present and the modulator works) the head tunnel gasses flow, and heat the EGRT and the test passes.
a 10c resistor can be used in place of the EGRT and fools it. I see you are going to do that.
your not guessing you are correct.


what ECu #
what harness,stock?
is the EGRT correct for calif?

sorry for cash lost.
its just code 51s if car drives good and no limphome mode and MPG is good, all is good. do you get smog tested that it? why 51 worries?

this is the egrt spec.

http://www.fixkick.com/EGR-Gen2a.html#thermoprobe


a 10k resistor will make it pass, in most cases.
the silly tying does only 2 tests no 3.
key one dead cold engine, if resistance is infinity it sets code 52
then when EGR is commanded open , it waits a bit, for the sensor to warm up and checks it 1 time,pass or fail.
it is dumb.
fore example it dont check and see omg its 10k for ever. (1996 it goes super strict testing)
do no not buy a new sensor just test it.

I bet its ok.

does the EGR open by itself hot, when you gun the throttle?, (need mirror to see it, facing engine, parked, brakes set and not in gear) ok i see you did.
but the stall test would make the EGR go roasting hot. but the above test is acid test. can ECU open the EGR main.

my guess.
EGRt bad (nah)
wires bad.
wrong ECU.
if the ECU is federal then the EGR is not used at all..... no code 53 pulled sensor, is that.
the FED car has no EGRT. so now 53s for missing EGRt.
easy to test and see doing that. no ripping ecu out and reading tag

oops my bad I think the last year 1995 all ECU use CALIF setup, EGRT.\\

see this yet, shows them all, USA
http://www.fixkick.com/ECU/EPC-ECU96-98/...9-95NA.pdf

ECU:
dash 70Exx

EA0
EC0
and ED0
gee looks like dash 70xxx is all EGRT ecu's if you look close. 1995

[fixkick]

for sure what ECU.???????
we start there for sure on any Code 51 or Code 53
do not spend money yet.
ok?

[jingusflob]

for sure what ECU.???????
we start there for sure on any Code 51 or Code 53
do not spend money yet.
ok?

Thanks for getting back to me so fast. My ECM is a 33920-70EC0. I do not have a smog requirement where I live. I just want the silly CEL to stop coming on all the time. I just finished reading another post about headers that you had previously answered. I have one of those Thorley headers with the EGR grove cut into the flange. I am wondering if that is part of my problem. But considering the CEL only comes on when I first start driving it for the day then I can get it to go out by cruising slowly, I'm not so sure. I am leaning towards the EGRT more and more. It does pass the bark test. And I see the EGR main move in and out when I rev the engine during the live test. So I know its working. I'm stumped. But i the 10K resistor will stop the CEL then I may end up doing that trick. I was just hoping I could figure out what is causing problem because I hate not knowing.

Thanks

[fixkick]

the test is easy, to find cause. (mostly) in your case.
use the test resistor. if the 51 ends.?
that means the sensor is bad or there is no proper exhaust flow across the sensor. (gee it dont take much flow,imo)
code 51 is not smart like 1996+ here.
it's a very crude and fast test.(obd1)
you said it has new EGR valve, so was that with or with out the EGRT inside? new.

if the resistor test passes, (if fails means wiring bad to ECU)
if it passes 10k test.?
and the EGRT passed the water test boiled then we know the exhaust flow is weak past it.
only why remains....

what can make the flow weak, well losts really (but not EGR main, its open you prove it)
the flow can be weak for 4 reasons, my guess.
1: the gasket on those header put on wrong causing the EGR port there to be blocked, and no flow there, but this error would make the stall test fail.
2: the head tunnel packed or was necked down fooling us. 10mm is size clean, here 1/2" bore. what if was 1/8" and packed.? oops.....
3: all quadra port egr injectors packed but 1 good?, fooling us that stall test passes.?
4: The cat is too big, causing the back pressure wrong and the EGR mod to be weak and the flow now weak. not dead but weak. yes this is a silly way to do EGR but is here. sadly.

i sure you know the status of the path that its Ok or now, so will go farther, if not...

id go the 10k ohm resistor of any kind, just some jumper clips there, attach it and see.


I understand you clearly " hate not knowing", me too,, i always think its something going to get worse. (or something I left loose)

we can find it, but the 10k ohm test is important.
as is the boiling tests. my guess is you reused the old EGRT..

most EGRT in most old EGR mains, are packed solid in carbon. and must be removed and cleaned.
to be re Used the sensor , must be clean. just a naked probe in the flow of exhaust gasses.

also I worry that code 51 might cause the ECU to do other odd things, a punishment of sorts (like retarding spark when it fails to prevent Ping detonations) Like modern cars do with Knock sensors.
we do know the most old sidekicks did not do punishments, 89-91. for EGR. (well if not stuck open)
most EGRTs do not fail, ever. just pack up. it's just a thermister and vary robust. (a passive device too)