7M4EVR;1969804 said:
You're chasing your tail, the car will run with a bad IAT or even a bad afm for that matter. It has default values it will run in those cases.
fuel and vacuum troubleshoot
- Thread starter 7M4EVR
- Start date
You're chasing your tail, the car will run with a bad IAT or even a bad afm for that matter. It has default values it will run in those cases.
Okay I only have little time at the shop tonight so iIwont worry too much about that then and will focus on other troubleshooting steps..but...where exactly is the IAT sensor since now I'm curious....
If all you have is a code 24 then it is not the source of your problem, as it should be close enough to run okay with the default value for air temp.
The concern would be that the AFM signal is also bad since they share the same sensor body and wiring. If code 34 is set (bad AFM) the car will run in limp mode up to 3000 rpm. Some AFM failures aren't severe enough to set code 34, and the ECU uses the bad AFM signal thinking its good and runs badly or not at all. Best course of action is to verify correct operation of the AFM with a frequency counter on the KV signal. The AFM And CPS signals are primary, the ECU needs those to run, unlike temp sensors and TPS which are secondary.
The concern would be that the AFM signal is also bad since they share the same sensor body and wiring. If code 34 is set (bad AFM) the car will run in limp mode up to 3000 rpm. Some AFM failures aren't severe enough to set code 34, and the ECU uses the bad AFM signal thinking its good and runs badly or not at all. Best course of action is to verify correct operation of the AFM with a frequency counter on the KV signal. The AFM And CPS signals are primary, the ECU needs those to run, unlike temp sensors and TPS which are secondary.
Thank you guys...grrrr came out to shop to find a lot of coolant had leaked out from the heater core hose behind the head...yeah the one that really sucks to get to....looks like I won't get to troubleshooting tonight but will get back out there later in the week and report back
3p141592654;1969819 said:
Thanks man...can u briefly explain frequency counter on the KV signal? Is that different than using an ohmmeter to check the resistance on the terminals per the tsrm?
And JJ...I didn't just pull the efi relay and expect it to clear my code, at first my AFM wasn't plugged in so after plugging it in I thought that might just have taken care of the code....or are you saying pulling the efi for 30 sec will not clear codes even if they are fixed?
Most multimeter have a Hz function to measure frequency. Looking at the Kv signal, you should see 15-30 Hz at hot idle, and the frequency should ramp up with more load in a predictable way. If you have a piggyback like an SAFC, it will also show the Kv frequency.
Pulling the efi relay will not clear codes is what JJ means. Wouldn't it make sense to interrupt power TO the ECU, rather than FROM it to clear codes?
Hint: the ECU energizes the EFI relay.. so the ECU must be getting power elsewhere for it to keep memory and be able to energize the EFI relay... no?
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Hint: the ECU energizes the EFI relay.. so the ECU must be getting power elsewhere for it to keep memory and be able to energize the EFI relay... no?
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Last edited:
http://www.supramania.com/forums/showthread.php?96313-7mgte-code-51-messed-up-idle-runs-rough
Right...so need to disconnect power from battery then.. Searched about a week ago to try and find out how to do thia and found jdubs post @11:05pm back in 2009...so that's where that idea came from...sorry Jdub lol
Right...so need to disconnect power from battery then.. Searched about a week ago to try and find out how to do thia and found jdubs post @11:05pm back in 2009...so that's where that idea came from...sorry Jdub lol
In that case why does the tsrm say to pull the efi fuze to clear codes???
http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=FI&P=25
http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=FI&P=25
6 posts to determine fuse != relay. Oh well....
Reread the first post and realized I missed the key point that fuel pressure drops after 5-10s. As asked in post #25.
You should read the base fuel pressure of 36psi when doing the above test with engine not running, and it should hold steady for as long as you run the test.
http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=FI&P=73
Reread the first post and realized I missed the key point that fuel pressure drops after 5-10s. As asked in post #25.
You should read the base fuel pressure of 36psi when doing the above test with engine not running, and it should hold steady for as long as you run the test.
http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=FI&P=73
Okay I will be going to the shop after work tomorrow to jump FP and B+. For the sake of time since i only have a few hours out there i want to know where to go fron there....
if I can't get it to read as high as 36psi I know what to check but if higher than 36psi on my afpr gauge, and it doesn't go down after adjusting the screw on the afpr, I am to assume the afpr is not functioning properly.... But if it is reading higher I wouldn't have my symptoms correct? I mean it would still continue running just very rich from the added fuel pressure right?
If it checks out and I CAN get it to steady @ 36psi I'm ready to move on...and since the AFM is ruled out because it would still idle off of default values, my CPS is lining up at TDC (still not sure if it is a perfect 10° BTDC yet because i cant use a timing light until its running) what should I move on to? I'm thinking injector wiring, coil pack/plug wires.
Just want to have an idea on where to move on to next in case that part of the fuel system passes the test.
if I can't get it to read as high as 36psi I know what to check but if higher than 36psi on my afpr gauge, and it doesn't go down after adjusting the screw on the afpr, I am to assume the afpr is not functioning properly.... But if it is reading higher I wouldn't have my symptoms correct? I mean it would still continue running just very rich from the added fuel pressure right?
If it checks out and I CAN get it to steady @ 36psi I'm ready to move on...and since the AFM is ruled out because it would still idle off of default values, my CPS is lining up at TDC (still not sure if it is a perfect 10° BTDC yet because i cant use a timing light until its running) what should I move on to? I'm thinking injector wiring, coil pack/plug wires.
Just want to have an idea on where to move on to next in case that part of the fuel system passes the test.
Well an engine needs three things, fuel air and spark.
If you have each of these things happening the next thing to check is timing, making sure these events are happening at the proper times.
After this, if everything checks out so far, make sure that you're getting a good spark and enough fuel to get a complete burn. You can never have too much spark but you can have too much fuel.
When a car normally starts and then starts to die shortly after you probably have a fuel issue. If it's not a fuel issue then one of the electrical components are getting far too hot(Shorted) for the few seconds its running.
If you have each of these things happening the next thing to check is timing, making sure these events are happening at the proper times.
After this, if everything checks out so far, make sure that you're getting a good spark and enough fuel to get a complete burn. You can never have too much spark but you can have too much fuel.
When a car normally starts and then starts to die shortly after you probably have a fuel issue. If it's not a fuel issue then one of the electrical components are getting far too hot(Shorted) for the few seconds its running.
Cleared all codes then jumped FP and +B. When ignition is on I do get 36 on my afpr gauge. BUT I only get like 10psi on my afpr gauge and low vac when the car is idling.
For some reason it does stay idling now its just very week, smells like fuel (even though gauge reads low?), and still if I give it gas it dies . I reset my cps timing to make sure it was good and its on and it is. When I unplug the AFM while idling all the sudden the idle gets better for a couple secs then completely dies.
If I take off a vac line the idle fluctuates. After I had given up for the night checked codes and now I have code 11 out of nowhere. I'm even more confused now than I was before.
For some reason it does stay idling now its just very week, smells like fuel (even though gauge reads low?), and still if I give it gas it dies . I reset my cps timing to make sure it was good and its on and it is. When I unplug the AFM while idling all the sudden the idle gets better for a couple secs then completely dies.
If I take off a vac line the idle fluctuates. After I had given up for the night checked codes and now I have code 11 out of nowhere. I'm even more confused now than I was before.