Help me simulate an EGR system... Car dies and will not easily restart.

[bobafett]

Ok, here is the story this time:

I can zoom around in my car like normal, it runs and drives as I would expect (other than the battery light coming on every once in a while when I am flooring it for a few seconds or if I am going down a hill on full decel for a while - lol).

However, sometimes I get a CEL (check engine light) - but I am not sure what triggers these lights.

I have checked and once I got 'Engine Coolant Temp Sensor unplugged or defective' which is fine, cause mine is unhooked, and the plug is being jumped by a toggle switch in the cabin.

The other CEL I have found is an EGR Lift Valve code. Now this would be cool except that I am using a B16 intake manifold, which doesn't have provisions for an EGR valve. Also I don't WANT anything to do with EGR. So currently my EGR wiring has been pretty much unplugged, and is dangling in the engine bay.

Now I don't 'mind' having a CEL, but this one presents a problem:

IF, I have a CEL, when I come to a stop, the car tends to want to stumble and die really easily. Unless I am at 2000-2500 rpm or higher, AT ALL TIMES when starting to slip the clutch, the car will die. If I try to do a 1000 or 1500 rpm slip to get the car moving it will die. Now I don't mind killing it, but when it dies like this, it won't start again for about 10-15 minutes.

I am assuming (but haven't been able to check the code that's occuring when this happens) that it's the EGR code that is screwing the car up. However it might be true that when my fan is on, the temperature of the car looks WAY too high and the ECU won't let it start. I just thought of that, and havent tried shutting the fan off before restarting the car.

If the CEL has NOT come on yet, the car will take off normally, and I can start and restart without any trouble at all, so it is definetly related to something that is causing the code.

Any ideas? My first thought was to get a resistor on the egr wiring i have, so that it will simulate a normal value, and keep the ecu happy. for the fan jumper i could do the same thing, so the car sees something like 210 degrees, and thinks to turn on the fans. instead of some wierd signal that it sees when hardwired. :)

[shepherd79]

here is what i dont' understand. why don't you fix one problem at a time.
i don't understand why you have engine temp sensor is on togle switch. why can't you just plug it in.
as far as EGR not working, well i can tell you one thing, it would be a bitch to make it work. the problem is that valve opens up and down with vacuum and sensor is registering the opeing and closing of the valve. so i don't see how you can simulate the opeing and closing of the valve.
why don't you get a20a4 ecu. they didn't have egr or o2 sensors.

oh and if you want to know how it works, here http://vehicle.berkeley.edu/Publications/EC/teske_ms_thesis.pdf#search=%22egr%20valve%20simula tor%22

[AccordEpicenter]

plug in the egr, run a vac line from the intake manifold for it, and just let it hang in the engine compartment somewhere

[bobafett]

well i havent fixed the problems because i have been moving and i basically got the car to a running state the day before i had to be out of my house. i have not had any time to work on the car, so all i have to go on are the problems that have occured during 2 brief test drives, and the 2 legs of the trip to get the car to my new place.

the temp sensor is unplugged and jumped because i have had trouble with the fans not coming on in the past. i have replaced EVERY temp sensor, and the fan switch sensor, and thermostat etc, all with oem honda parts, and the fans still wouldnt come on sometimes.

because i really don't want to overheat my new engine i decided to take matters into my own hands and just jump the sensor so i can keep the fans running once the car gets up to operating temps.

as for the egr simulation, it does sound like a bitch. a20a4 ecu seems like a good way to do it, but it is probably based on an 88-89 ecu, which I would guess has other BS to deal with that I don't have on my car.

i 'could' throw my egr crap back on but I had to hack up the wiring to fix my tps to get it working with the 88-89 style tail.

I will need to get down to a junkyard and pull off the egr valve and wiring. :) and probably should pull the whole black box while I am at it. heheh...

I am getting fed up with this BS, it may be time to roll standalone sooner than I thought. still need to get an electronic dizzy situation working though. :)

[carotman]

The fans aren't triggered by the Engine temp sensor (for the ECU)

If you get a code for the temp sensor, you'll have a hard time starting and idling cause it will run way too rich.

[AccordEpicenter]

change your relay for the fans, somtimes they get defective and only work somtimes

[bobafett]

The fans aren't triggered by the Engine temp sensor (for the ECU)

If you get a code for the temp sensor, you'll have a hard time starting and idling cause it will run way too rich.


Interesting, what triggers the fans then? I was under the impression that the fans are triggered by the sensor at the bottom of the radiator, which I thought was called the fan switch. This is the sensor I have been talking about. When I jump that sensor, as long as I have power to ignition, the fans come on.

Is it possible that the ECU is throwing me a code for a different sensor? I DID have some issues with one of the sensors having to be rewired because a wire got old and brittle, it is possible I wired it up backwards or something. :)

The car idles at basically 11:1 so your comment about the car idling way too rich is certainly dead on! I will see if I can diagnose which sensor is throwing the code...

Can you tell me if the "Engine Coolant Temperature Sensor" is one of the two on the thermostat housing then?

[AccordEpicenter]

it should be, one is a thermoswitch and the other is an actual temp sensor.

[2oodoor]

bobafett you come up with some good ones., We used to run potentiometers on the temp sensor to fool the ecu to run rich or lean on slowstangs. I never hear of using a toggle switch. That seems like it would set a CEL. toggle switch would read as volt spike right.
Also you dont want egr on during idle, ever. I dont know what exactley to say , I will read the thread again when I can think about it.
What your saying about the battery light coming on on decel also is telling me of an engine/transmission ground going to the wrong thing. If your using toggle switch for any sensor it will set CEL because any of these read slow and do not all work at full reference voltage. That is why we used to use pot switches, or like volume analog switch to slowly adjust the voltage signal from temp sensor.You will have to get a pin out diagram of the ECM to disable the some of the things your wanting to do, like reading the egr position readings going to ECM, I may be able to help with that. pm

[bobafett]

it should be, one is a thermoswitch and the other is an actual temp sensor.

ok, here is my understanding of the EFI sensors and fan switches... maybe you guys can let me know if i am on the right track or not.

1. fan switch - located at the bottom of the radiator, by the bottom radiator hose. this switch activates the fan relay while the car is running and the temperature is above <SOME> setting (probably around 190 degrees).

2. water temperature for dash/gauge - located on the thermostat housing. this is the single wire that plugs onto the smaller sensor on the thermostat housing. this does nothing but report water temperature to the gauge, this should never affect how the car runs because it's soley used as a gauge.

those are the ones that I feel I understand decently well.
but there are two larger sensors in the thermostat housing. these two are somewhat confusing to me. ONE of these two had a busted wire INSIDE the plug, so I had to dismantle it and rewire it, but since I am not sure which sensor performs which function, I don't know which sensor I might have interfered with.

3. temp sensor 1 of 2 - located on thermostat housing. this sensor sends a temperature to the fan relay when you shut the car of, and if the temperature is above a certain temperature, it will run the fans for 15 minutes. I would guess that this sensor would not effect the running operation of the car, and wouldnt cause me to throw a code.

4. temp sensor 2 of 2 - also located on the thermostat housing. this sensor must be the one that sends a reading to the ECU, right? if the fan switch sensor has nothing to do with the ECU, then this would be the only sensor left to send a reading to the ECU. it would make sense that if this was the sensor I rewired, and I did it wrong, that the ecu gets confused and throws a code, and it would also explain to super rich idle. are there ways of testing this sensor so I might verify its functionality?

I will try to look at the sensors and maybe take a picture to show you guys which sensors I messed with.

the potentiometer method makes much more sense to me, as a way to falsify the value of the sensor, but I would have no idea which pot to buy. :(

the next step is getting an a20a4 ecu from greatdane so i have an ECU that doesn't need EGR or o2 sensors! :) that will help at least some of the problems.

thanks for your help so far guys

[carotman]

4. temp sensor 2 of 2 - also located on the thermostat housing. this sensor must be the one that sends a reading to the ECU, right? if the fan switch sensor has nothing to do with the ECU, then this would be the only sensor left to send a reading to the ECU. it would make sense that if this was the sensor I rewired, and I did it wrong, that the ecu gets confused and throws a code, and it would also explain to super rich idle.

BINGO

There is a testing procedure in the shop manual. This is basicaly a thermo resistor.

[2oodoor]

if your taking your time on this i can look at the ecu breakout , i have shopkey software at work, if we can see what the egr sensor is talking to and why, it could be sent to never never land, only a chance .temp sensors and thermistors may be controling idle speed, horrors, and I would not be surprized if a lot of what your cutting has anything to do with powerband mixture, just like you said it runs like a scalded cat sometimes then some condition happens on decel or idle???
I have come to understanding that Honda engineers really put forth a lot of effort to obtain perfect idle and off idle rpm number variances, but tinkering just a few things or a simple fan relay problem can upset the plan so drasitically. I will keep up with this thread and give my 2 cents that seems to help ya even a little.
I reckon you got the ignition problem fixed, I will see if you put the solution in the thread , i dont remember if you ever told us what fixed it. The battery light coming on is really making me think, that is just wierd and sounds like a miswired relay, i am always looking for ways to get around throwing money at a problem by buying something that you can do yourself... cheers.
Guy

[bobafett]

lol the ignition problem was BAD. :( i had changed cams and hadnt set my valve lash. there was no compression. as soon as i set the valves the car came roaring to life. :) i feel like such a dumbass sometimes... i thought I had set the valve lash when i put the cam in, but i guess not.

now i am on to an equally puzzling and bizzare issue! hehe. but i just paid thegreatdane for an a20a4 ecu, so that will help out with the EGR issue and eliminate the need for 02 sensors, so that can't hurt!

[AccordEpicenter]

cool let us know how it goes chris.

[mkymonkey]

yeah i would like to know how the ecu that greatdane gave you works out...i really want to get rid of my freaking 02 sensors and the egr :thumbup:

[shepherd79]

yeah i would like to know how the ecu that greatdane gave you works out...i really want to get rid of my freaking 02 sensors and the egr :thumbup:
if you do that, you will never pass CA emission or visual test.

[mkymonkey]

its ok im mexican :D

[bobafett]

its ok i dont have emissions where i live. :)

[2oodoor]

yeah i would like to know how the ecu that greatdane gave you works out...i really want to get rid of my freaking 02 sensors and the egr :thumbup:
monikey...I guess I need to read up on this greatdane ecu thing, if your FI how do you expect to run without O2 sensors. The ECU has to know the mixture somehow, it cant only assume what it initiates is what is happening. I need to know more about this aftermarket ecu scene.

[shepherd79]

it is not aftermarket ecu. it was sock Honda ecu for A20A4 engines in europe.
they run on closed loop. they have preset number that they run off.

[bobafett]

nothing too big, but I have a small update:

I stripped off the tape and loom, and RE-rewired both of the 2 wire sensors on the thermostat housing. now I am just using spade connectors instead of the plastic plugs, but i am using enough extra wire that there isnt any weird tension on the wire.

after fixing the first sensors wiring (the one I knew had been soldered poorly) I noticed that my OTHER sensor also had one wire break for me. so I ended up just rewiring both of them.

the good news is, at least from my 10 minute idling in the driveway, there were no CEL codes, and my engine light turns off properly when I have the ignition on, but am not starting.

so i think the whole time my main relay has been ok, and it is just wires haveing intermitant connectivity.

also i played with the SAFC and pulled like 25% fuel (i think my fuel pressure is still set too high) and my idle leaned out to the proper 14:1 ish AFR.

I do have a basic question though...
In a car without anything to assist cold starts and cold idling, (might have cold advance hooked up, i honestly cannot remember, but i definetly have no fast idle valve or iacv. :) ) will the car idle rich or lean?

reason I ask is because it idles at like 10-11:1 afr normally. now for the first time i pulled some fuel out with the safc and got the idle up to 14:1AFR, but since it wasnt super rich, it warmed up faster, and then the afr got much higher.

obviously i plan on tuning the car when its warmed up, but I want to make sure that the car SHOULD lean out when warm, especially considering i have no idle or cold assistance of any kind. i know that as the car warms up the idle gets higher and much smoother. :)

hopefully today after work i can sped a bit of time trying to get it to run a bit better.