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1G Code 43 EGR after 2g head drop on 1g 7bolt block

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sacrileger

Proven Member
288
43
Jun 26, 2016
Orillia, ON_Canada
I have dropped 2g head, including intake, on my 1g 7bolt block recently - '94 Talon, non-turbo, most likely w/ California Emissions ECU settings . I have also installed the 1g CAS, throttle body and EGR valve on the 2g head; among others. The timing of the engine should be 5 degrees BTDC +/- 2 degrees. Mine is 2 degrees BTDC since I ran out of travel on the 1g CAS while setting the timing.

I drove the car for the first 50 miles w/o any CEL. After about the first 50 miles of driven distance, driving on hwy at cruising speed, the CEL came on - veeery slooowly, as if hesitating. It did not flick on. There was no indication of misfire nor any other engine irregularity that I noticed while driving it. The engine runs fine. And now the CEL stays on - of course since I did not clear the codes.

I checked the ECU and pulled a diagnostic trouble code #43 out of it. My manual tells me this code is generated any time there is a problem with:
1/ harness and connector
2/ EGR temp sensor
3/ EGR valve
4/ EGR solenoid
5/ EGR valve control vacuum

Given that the code #43 did not appear immediately after I started up the engine, my suspicion is that the problem is #5, valve control vacuum, but don't know how to confirm it.
There were no problems or code #43 calls with the 1g head on. This problem appeared after the switch.

Before I get into any of this testing:
https://tinyurl.com/yapb28up
would you gents know what my problem might be? thank you.
 
The ecu just sends 12 volts out to the sensor, if it does not see 12v being used it triggers the check engine light

The only time you will actually get a check engine light from a sensor is if the sensor is electrically blown, or left unplugged. The computer has no idea if the sensor is actually working

So if you are running a 1g ecu and harness you should have the egr sensor plugged in. It doesn't actually need to be hooked to anything
 
Without the EGR Temp sensor in the EGR valve the California ECU will throw a 43. Get a Federal ECU or try inserting a 1k resistor in at R129. If it's a 90 ECU that may not work because the Fed and California code wasn't integrated early on.
 
The ecu just sends 12 volts out to the sensor, if it does not see 12v being used it triggers the check engine light

The only time you will actually get a check engine light from a sensor is if the sensor is electrically blown, or left unplugged. The computer has no idea if the sensor is actually working

So if you are running a 1g ecu and harness you should have the egr sensor plugged in. It doesn't actually need to be hooked to anything

I have not taken the ecu out to read its part number, but I am 99+% certain it's the original 1994 ECU that came in all Talons at that time. My previous quip about california emissions was just a that; a quip. This car was purchased in Canada - which does not mean anything actually w/ NAFTA, but...

In any case, I double checked connections, they appear to be fine. I am inclined to believe that this error #43 is somehow generated by a vacuum leak. After the switch from 1g cyl head to 2g head, I tried to hook up all vacuum lines where they belong; however, it was mostly re-connecting to parts that were connected before the switch. For example, there's an extra vacuum line coming from the 2g intake plenum that I had no idea where it goes so I plugged it.
Rather than perform the EGR temp sensor test as in the link in my first/initial post, I wonder if there's another, quick and dirty, way to test the sensor with it being installed, i.e. connect voltmeter to the el. connector and check for certain resistance while cold. Or hot after a run.
 
Yeah it's just the sensor. The computer has no way to monitor engine vacuum or specific tables to determine if the emissions part is working. The ecu triggers the light when it senses that the sensor is not using the supplied 12 volts being sent to it. (Or does not sense resistance in the wire) It's best to find a used part for these cars than to bother with a new part

I have a self made egr plate made from an old license plate, and just left the sensors plugged in with no vacuum hoses on them, tucked under the back of the intake manifold. No codes

(A little clarification, the sensors themselves have no hoses on them but are still plugged into the electrical connectors. The vacuum hoses from the motor are capped so the engine does not have a vacuum leak)

Also my 2g is only a vacuum control valve, and has no sensor other than the vacuum valve on the firewall, I am not aware of what the 1g sensor looks like
 
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I have not taken the ecu out to read its part number, but I am 99+% certain it's the original 1994 ECU that came in all Talons at that time. My previous quip about california emissions was just a that; a quip. This car was purchased in Canada - which does not mean anything actually w/ NAFTA, but...

Yep, the quip threw me off. IIRC, the 94 cars all had the more stringent California style emissions.
 
Yeah it's just the sensor. The computer has no way to monitor engine vacuum or specific tables to determine if the emissions part is working. The ecu triggers the light when it senses that the sensor is not using the supplied 12 volts being sent to it. (Or does not sense resistance in the wire) It's best to find a used part for these cars than to bother with a new part

I have a self made egr plate made from an old license plate, and just left the sensors plugged in with no vacuum hoses on them, tucked under the back of the intake manifold. No codes

(A little clarification, the sensors themselves have no hoses on them but are still plugged into the electrical connectors. The vacuum hoses from the motor are capped so the engine does not have a vacuum leak)

Also my 2g is only a vacuum control valve, and has no sensor other than the vacuum valve on the firewall, I am not aware of what the 1g sensor looks like

This is the EGR gas temp sensor I am using:
https://tinyurl.com/y7qcpjk2

As I mentioned earlier, I dropped 2g cyl head onto 7bolt 1g block. My 2g cyl head has an MDP sensor to measure the amount of vacuum in the intake manifold which is used to ensure that the exhaust gas recirculation emissions control system is working properly. My 1G EGR valve is using the above temperature probe for this instead, while the 2G head I put on uses the MDP sensor which I left unplugged since I dont have a connector for it on the 1g setup.

I tried to test the EGR gas temp sensor. The first test is to turn the ignition key ON (engine not running) and check terminal #1 on the harness side for supply voltage to the EGR temp sensor. It should be 4.3 to 4.7 volts. Mine is 3 volts. My manual does not tell me what needs to be done if the voltage is out of spec.
Any suggestions why the voltage is low and where to look for the fix?
 
http://www.dsmtuners.com/threads/egr-temp-sensor.357998/

You'll definitely will get a CEL with the sensor unplugged since it's not getting the resistance reading that the sensor is sending to the ECU. For the ECU will see this as an "open loop" situation, throw a code and get the CEL light on for the operator to get checked.

If you now got bare wires since they were pulled out of the plug, you can take a 62Kohm, 1watt resistor and solder it between the two wires and wrap all of this up real snug with electrical tape. This will make the ECU see that the sensor is operating normally and you'll will never get a CEL light again with this small mod.

Good luck-DSM
 

My case is a bit different. It probably was not that clear when I described the problem. I actually transferred the EGR valve with the EGR gas temp sensor in it onto the 2g cyl head and connected the EGR temp sensor to the harness connector; thus, ecu. My problem now is that the supply voltage to the EGR temp sensor should be 4.3 to 4.7 volts and mine is 3 volts.

I could kluge/fake the connection with the suggested 62Kohm, 1watt resistor and solder it between the two wires. However, I actually do need this valve to correctly recirculates hot exhaust gas into my intake stream during cold starts so the fuel can atomize and engine run better since this will be my daily drive and winter beater.

Edit: On the other hand, clearly, the 1990-1992 4g63's did not have this more stringent California emissions requirement and there is no record that these '90-'92 cars ran like crap in Canadian winters so maybe the EGR temp sensor can be faked w/o a performace hit and is not necessary after all?
 
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Couldn't you just put a 1g 7bolt intake manifold back on the 2g head and it would solve your problem?
The 1G head is a total write off:
https://tinyurl.com/ybyx3r5x
so I put the 2G head that was in good shape on.
I think I might just go with the suggested 62Kohm, 1watt resistor soldered between the two wires. How bad can it be? The previous years did not have this requirement.

Edit1: Furthermore, given the purpose of EGR, I wonder if I even need EGR valve at all.
https://en.wikipedia.org/wiki/Exhaust_gas_recirculation
Any thoughts on that? Apparently EGR along w/ other sensors can be deleted if one does not care about passing emission test:
https://tinyurl.com/y7ggmn7k

but gas mileage will suffer slightly:
https://tinyurl.com/yc6q4cxj

Edit2: When the engine coolant temperature is low, when the engine is at idle or when a wide open throttle operation is performed, the EGR valve is kept closed, achieving no EGR.
In normal vehicle operation performed after warming up of the engine, the EGR valve is opened to carryout EGR. In normal vehicle operation performed after warming up of the engine, the EGR valve is opened to carryout EGR. The EGR flow rate is controlled by the EGR valve so as not to decrease the driveability. The EGR system contents: EGR valve, EGR solenoid, Connecting hoses. The engine control module checks the operation of the EGR system and, if a trouble is detected, lights the Check Engine/Malfunction indicator lamp to warn the driver of the trouble.
 
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New info: error code #43 which triggers engine light on (CEL) clears itself when the outside temperature is below 0 degrees celsius. The light goes off. As soon as the temperature goes above zero, the sensor triggers CEL again. This pattern works like clockwork now, ... morning temperature below zero, no CEL, temperature rises above zero, CEL.
Any idea what is going on here? I already bought the 62Kohm, 1watt resistor to fool the ECU; however, I'd prefer to fix it. thanks.
 
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Or just swap in another non 94, non ca ecu

http://www.dsmtuners.com/threads/swapping-my-california-ecu-with-a-federal-ecu.147707/


The egr valve is only there to reduce emissions and improve fuel economy. It is only used after engine is warm under low load

Honda used the egr valve very strategically in their d-series motors to increase gas mileage by 20% compared to non egr equiped models. Other than slightly reduced gas mileage, and cleaner combustion chambers and cleaner intake manifold, the egr valve has no effect on engine performance or reliability.

Ive had the egr valve deleted on my 98 z28 for over ten years an 80k miles. You will be fine without it
 
If you had ECMlink you could just turn the code off :)

and it's cracking me up that chrysler kid is talking about hondas and camaros on a dsm forum and a guy by the name of @sacrileger likes the post.

sorry I'll go away now.
 
I also got this code, a few months after I swapped the 4g63T into my mirage, it popped up after a long freeway drive, it went on and off a few times intermittently eventually it stayed on at all times, it's not the worst code to get from a 1g dsm ecu, but I like to take care of any issues if I can, so back to what ended up fixing my code 43, I added some fuel system cleaner to the tank, and then drove the car around for a few hours, and the code went away while I was driving the car, it's been 3 months since, and so far it has not come back on.

Honesty if I had the time I would have done more direct service to correct the code, but it was late at night and I was at a seven eleven and thought why not give the 7 eleven brand fuel system cleaner a try for $6 it's worth a try worst case I'm going to get the car home and fix it there.
 
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If you had ECMlink you could just turn the code off :)

and it's cracking me up that chrysler kid is talking about hondas and camaros on a dsm forum and a guy by the name of @sacrileger likes the post.

sorry I'll go away now.

Mechanically every gasoline engine works the same way. Bang suck blow. Theyve made a few design tweaks along the way.

I stopped modifying dsm's when the ls1's became more feasible to own. :) I got into dsm's because they were faster than hondas
 
I'll just add more info to this thread:
Even after I installed a resistor to fool the ECU as was suggested above, nearly a year later, I am still dealing with CEL. I am going to find out this winter if the CEL goes away once temperatures drop below 0C as was the case during the last winter. Some of you smart ladies may quip that I should have installed the 62Kohm, 1watt resistor as suggested instead of 68Kohm, 2W resistor 2% margin of error (see below). Needless to say, that was the closest I could find.

However, while reading up on some other issues regarding ECU codes I came across this post where the claim is that error 43 also appears to be common when the ecu capacitors have to be replaced.

1g Code Reader - CEL CODE READER

Which sounds plausible; however, it would be odd that the car did not have CEL issues prior to my dropping 2g head (plus some other minor 1g/2g components mix and match) and suddenly I get CEL when temp goes above 0C and CEL goes off with freezing temperatures.

Nevertheless, should I have to start fixing and replacing capacitors in my ECU, here's a good way to start and decide what needs to be replaced:

http://www.ecmtuning.com/wiki/ecurepairhome

here's the resistor I put on

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