Project 1994 Car Is Running.

Timing causing these is probably unlikely - knock sensor fault is cause by the ECM looking at a low resistance or reads ground on the signal wire. Similar to the IAT sensor - both could be an ECU issue or more likely a bad wire to the sensor. As a cooked ECU will give you some other headaches as well - but I would say that to replace at the end of your troubleshooting - unless you have a spare one handy.

Swapping those components is fairly simple and if it fixes both or either fault, I can get them at the junkyard.

I am more afraid that there is some kind of wiring problem.

I do happen to have a spare ECM (actually I have several) that I can swap in.

I suspect it is actually one of the connectors to the ECM and not the ECM itself.

When I was swapping it before I noticed a wire to the ECM was spliced into a separate wire that led to the sensor on the aft side of the engine.

I don't know for sure, but I think the previous owner tampered with the ECM connector(s).

Tomorrow I will swap in another ECM and see if anything changes.

Bike,

What was causing the car to have no spark?

Jay in MA

I drove the car today and same thing happened.The car "bogs" when first going, then picks up speed.

 

I am going to purchase a timing light (my light broke) and check the timing.

The check engine light comes on and goes off intermittently.

I did the jumper in the diagnostic plug and got codes 24 and 52.

My manual says problem with IAT and problems with knock sensor circuits.

Both could be due to bad ECM. I wonder if bad timing could also give these IAT and knock sensor codes?

I will check it again tomorrow.

Any experience with this symptom or these codes??

Bike,

What was causing the car to have no spark?

Jay in MA

I drove the car today and same thing happened.The car "bogs" when first going, then picks up speed.

 

I am going to purchase a timing light (my light broke) and check the timing.

The check engine light comes on and goes off intermittently.

I did the jumper in the diagnostic plug and got codes 24 and 52.

My manual says problem with IAT and problems with knock sensor circuits.

Both could be due to bad ECM. I wonder if bad timing could also give these IAT and knock sensor codes?

I will check it again tomorrow.

Any experience with this symptom or these codes??

Today I took four other ECM's I had in my garage and one at a time I slaved them in and took the car for a drive (except for ECM #2 - it did not even start with that one). Most of the time the fault code of 52 came and everytime the CEL came back on.

I followed the Toyota repair manual and found that the spliced in wire to the ECM turned out to be for fault code 52.

It is the knock sensor. I could not get the connector off the sensor (it is on the aft side of the engine) because it is too tight.

I noticed that the regular wire at the ECM for the knock sensor was cut and spliced into the ECM with coax wire was a replacement.

The outer shielding was grounded on the firewall and the other end was touching the inner core of the wire. I straightened that out and cleared the fault code and went for a ride. It seemed like it was running fine, did not hesitate and the CEL did not come on again. I took my daughter for a ride and it was a big disappointment because the CEL came back and so did the same fault code. I have the knock sensor from the original engine and I metered that and it checked good. If I can get the sensor off the replacement engine I will try and swap it out tomorrow.

I will also check the wiring. I may even run another wire (not coax - no shielding). I have other engine main electrical harnesses with the connector and might need to use a piece of one.

I checked with Kragen Autoparts and they sell new knock sensors - the Nippondenso is $169 and the Mitsubishi is $193.

I think I will just use a used one.

If I can get this knock sensor problem fixed, then I think the car will run great and be ready for sale.

Further updates to follow.

The CEL is off, but comes on intermittently while driving.

It gives code 52 which is knock sensor fault.

I changed the knock sensor with a good one, checked the wires, and tried various ECM.s.

After re-setting the CEL it is now only intermittent.

Today I changed the spark plugs and drove it around.

The change was noticeable, but the light still came on (flashed briefly several times and once stayed on for about 10 seconds).

I tried to determine if it did it in a certain gear or speed and it appeared random.

The car seemed to skip, the light came on, then it went out and the car was normal.

It is hesitating - when the light comes on, like it was not firing on one (or more) spark plugs.

I think I will check/change the spark plug wires (I did check them before, but problem is intermittent).

The distributor (cap/rotor) is brand new and the timing was set to 10 DBTDC.

Anyone have any ideas??

The car was getting a CEL with a fault code of 71 (EGR system).

I was prepared to clean or replace all the EGR components, but I changed the ECM and reset the CEL.

The light has not come back.

The car has been sold.

The owner came back with the car because it has failed the California smog test (emmission check).

It passed all the exhaust gas tests, but the CEL stays on.

The code is still 71 and is an EGR problem.

The catalytic converter and O2 sensor was changed and still has an EGR problem.

I have to find the wiring for the connector on the EGR valve.

Bike you going to fix his car? if you are I hope you are going to charge him for your time - no such thing as a free lunch. If someone bought a car from me in the fall of 2007 and has a problem like that and brought it back to me - I'd tell him SOL and send him off. As soon as money changes hands. paperwork filled out, and we shake on it - its all his.

but they are friends of the family and I don't want to let them down.

I suspected they might have problems when I sold them the car, because I kind of fenagled the emission test that I had to do to sell it.

In CA there is another test every two years and now it has come around for the car.

The problem is that the two wires that normally come out of the engine main electrical harness and the connector to the EGR is not present.

I have to find the way to change the harness/install the wires/ or other to get it to pass the test with no CEL.

I have checked two other spare wiring harnesses (not complete) and found that they both have the connector.

I don't want to tear them apart to find the routing and where they go to.

Anyone have a color coded wiring schematic for the variations of 7th generation Corollas??

Bike you going to fix his car? if you are I hope you are going to charge him for your time - no such thing as a free lunch. If someone bought a car from me in the fall of 2007 and has a problem like that and brought it back to me - I'd tell him SOL and send him off. As soon as money changes hands. paperwork filled out, and we shake on it - its all his.

I understand what you are saying - and normally that is my business method as well,

 

but they are friends of the family and I don't want to let them down.

I suspected they might have problems when I sold them the car, because I kind of fenagled the emission test that I had to do to sell it.

In CA there is another test every two years and now it has come around for the car.

The problem is that the two wires that normally come out of the engine main electrical harness and the connector to the EGR is not present.

I have to find the way to change the harness/install the wires/ or other to get it to pass the test with no CEL.

I have checked two other spare wiring harnesses (not complete) and found that they both have the connector.

I don't want to tear them apart to find the routing and where they go to.

Anyone have a color coded wiring schematic for the variations of 7th generation Corollas??

Bike you going to fix his car? if you are I hope you are going to charge him for your time - no such thing as a free lunch. If someone bought a car from me in the fall of 2007 and has a problem like that and brought it back to me - I'd tell him SOL and send him off. As soon as money changes hands. paperwork filled out, and we shake on it - its all his.

I understand what you are saying - and normally that is my business method as well,

 

but they are friends of the family and I don't want to let them down.

I suspected they might have problems when I sold them the car, because I kind of fenagled the emission test that I had to do to sell it.

In CA there is another test every two years and now it has come around for the car.

The problem is that the two wires that normally come out of the engine main electrical harness and the connector to the EGR is not present.

I have to find the way to change the harness/install the wires/ or other to get it to pass the test with no CEL.

I have checked two other spare wiring harnesses (not complete) and found that they both have the connector.

I don't want to tear them apart to find the routing and where they go to.

Anyone have a color coded wiring schematic for the variations of 7th generation Corollas??

hey bikeman. take the bulb out of the speedometer cel assembly. that will take care of it.I can get a cluster out in less than 10 minutes. problem solved.

 

That is part of the CA emmission test requirements.

See my other post.

Problem is the wires from EGR to ECU.

Did you change the EGR modulator valve?

https://www.corolland.com/forums/index.php?...st&p=132780

See my other post.Problem is the wires from EGR to ECU.

Did you change the EGR modulator valve?

https://www.corolland.com/forums/index.php?...st&p=132780

See my other post.Problem is the wires from EGR to ECU.

I advised the current owner of the car to send in paperwork for the CA CAP program that will pay up to $500 to get the car to pass smog test.

It needs EGR and wiring connections for CA emission requirements.

I have the parts I took off a junkyard car and can supply them to the repair shop.

I don't have the time to change it all myself (although I could).

More to follow.