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Brah.
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Discussion Starter #1
I got jimmys kit about 3 weeks ago and installed it with an AEM ecu which includes a little wiring and setup of all sensors used (MAP, TPS, and O2) and loaded the map that jimmy runs in his car. At first glance everything seemed to be okay. So I attempted to run it and it would idle good but would flood when the throttle percentage was increased. So I checked over some things that could cause this. In doing that, I found that the TPS was reading around 3.75v at closed thorttle and 4.95 at open throttle. So i removed the TPS and fooled around with it till i got it reading a minimum of .25v and put it back on. It would then would read .25v at closed throttle and 2.86v at open throttle. I figured that was okay. But when i turned the car off and back on it went back to reading 3.5 at closed throttle and 4.95 at open and i could not get it to go below 3.75v and after awhile it would only read 0v or 4.95v so I called jimmy and he sent me a new tps i installed it. With the new sensor it would read 2.58 at closed throttle and 4.55v at open throttle so i figured that was right because it was a brand new sensor, and went to try to get the car running once again and it would do the same as before and idle great and full throttle was good, but anything else was nothing worth talking about. So i figured maybe it was the TPS input pin; so i took the EGT #1 input and changed the aem to read it as the TPS input to see if that could be the issue and i still got the same readings. I have even taken a multi meter to check to make sure the input voltage at the tps matched what was showing in the AEM to void out any unintentional grounding issues. Then figured maybe it was the tune i was trying to run so i got ahold of jdmeg2 who has the exact same setup as I do, and he sent me his tune. I uploaded it tonight and the car idles soooo much better than any other tune i have tried. But i noticed that when i cracked the throttle to what would be about 1/4th throttle the aem was reading it as 50% throttle because of the lack of a full 5v range that the TPS is suppose to have. So my question is.. why am i not getting my full 5v range on my TPS? I have ruled out any possability of it being the aem since i moved the input pin and am still faced with the same problems. Are there any other sensors that use a 5V reference that I could switch to in the event that the TPS 5V reference is faulty? Or maybe this sensor is also faulty?

For instance, At 0% "actual" throttle, the AEM reads 0% throttle. At 25% "actual" throttle the AEM reads 50% throttle. At 50-75% "actual" throttle the AEM reads between 95% and 100%. In other words, the throttle percentage read by the aem isn't linear at all when compared to the actual position of the throttle.


here is a link to the aem forum from where i was posting about this issue.


http://forum.aempower.com/forum/ind...ic,19860.0.html
http://forum.aempower.com/forum/ind...ic,19965.0.html


i have checked the 5v source and the sensor ground they are correct. no one on the AEM forum seems to know the answer to this.


Anyone have any ideas?
 

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how is the tps wired? kinda sounds like there isnt a good power voltage or a bad ground.

edit: also, are you running a MAP? or are you running TPS vs. RPM? never messed with AEM, but i have used megasquirt and you can switch between the 2. what kind of AFR are you running? how much vac are you pulling, if you can read that?
 

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Re: Fuji-Racing ITBS TROUBLES :(

Noah,

I agree with Bryan, the first thing I would look at is proper grounding for the TPS. A lot of the control sensors are grounded to the same ground through the ems. This allows the ems to correct for the ground voltage. If the sensors don't get grounded through the ems, you will get a voltage offset.

It would help also if (as Bryan has asked) we knew you were running MAP or TPS or a combination.

Bruce
 

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Brah.
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7,484 Posts
Discussion Starter #4
i am running MAP and TPS i have the TPS wired to a sensor ground and the 5v source is good and i have even moved the input wire for the TPS on the aem to make sure it was good.
 

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Brah.
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Discussion Starter #5
another thing i forgot to mention is that the TPS voltage change is not gradual it jumps quickly.
 

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Brah.
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Discussion Starter #6
For instance, At 0% "actual" throttle, the AEM reads 0% throttle. At 25% "actual" throttle the AEM reads 50% throttle. At 50-75% "actual" throttle the AEM reads between 95% and 100%. In other words, the throttle percentage read by the aem isn't linear at all when compared to the actual position of the throttle.
 

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Brah.
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Discussion Starter #9
there is and the AEM does adjust for the TPS but its something with the TPS that seems to be the issue. the voltage change does not match the throttle. the AEM is able to be adjusted so that it knows what volt is closed throttle and what volt is WOT (100%) the TPS should make a gradual change in voltage as it reaches WOT. the problem is that the TPS does not match what the throttle is really doing.
 

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Broken image.
 

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What year is the motor?

In my case (1.8l):

1) new TPS spliced into OEM TPS, using the 5V supply, ground and voltage output.

2) MAP spliced into the MAF harness (ground and output voltage) and OEM TPS (5V supply).

3) Air Temp sensore spliced into MAF harness (ground and air temp sensor output).

Note that the MAP and the TPS use the same 5V supply of the OEM TPS harness.

Also, you may try rotating the key in the TPS 180 degrees and see if that changes the idle and WOT voltage.

Bruce
 

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Brah.
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Discussion Starter #13
What year is the motor?

In my case (1.8):

1) new TPS spliced into OEM TPS, using the 5V supply, ground and voltage output.

2) MAP spliced into the MAF harness (ground and output voltage) and OEM TPS (5V supply).

3) Air Temp sensore spliced into MAF harness (ground and air temp sensor output).

Note that the MAP and the TPS use the same 5V supply of the OEM TPS harness.

Also, you may try rotating the key in the TPS 180 degrees and see if that changes the idle and WOT voltage.

Bruce


motor is a 97 in a 93 car

the TPS is wired in using the stock ground and 5v and i added in the sensor wire myself. for the MAP all 3 wires were ran straight from the ECU ground, 5v ref. and sensor wire. also for the AT sensor i ran the wires from the ecu. no wires were spliced into the MAF harness. now if i do rotate the TPS 180 it will change the volt readings for my open and WOT but the same thing happnes with the lack of a full 5v range and the TPS does not match what the throttle is doing.
 

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Noah-Send me exactly what you wired in where. A simple diagram of the wire colors to where & all grounds and we'll see what we can figure out. I'm thinking that the TPS is good and has something to do with the wiring. Still not ruling out the TPS but we've never had one fail yet and it seems odd that 2 would be faulty. We need to get it figured out. You can even call me tomorrow if need be. Also wanted to point out that the AEM needs to be able to recognize the MAP sensor that you are using.

Jimmy
FujiRacing
 

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Re: Fuji-Racing ITBS TROUBLES :(

Noah,

From what you are saying, you could possibly have a voltage offset in your MAP and TPS. There are five different grounds on the ecu and they all have a different purpose.

1. 1K Manual transmission ground (ignition on)
2. 2A Fuel injector ground
3. 2B output ground
4. 2C ECM ground
5. 2D input ground

The sensors are all grounded to the same input ground (2D) on the ecu. The ecm ground is not the one to use. The input ground tells the ecu what the ground reference voltage is for the sensors, and by all the sensors being grounded to that point, they all have the same ground voltage, and are not offset from each other.

The ecm ground is the ground for the actual ecm.

Verify that the MAP is grounded properly. An improperly grounded sensor can induce ground offsets.

Bruce

edit: I believe that the reference voltage is derived in part by looking at the sensor ground voltage. If you have an offset ground, that could mess up the vref.
 

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Brah.
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Discussion Starter #16
okay i have moved the TPS, AT and MAP grounds from 2C to 2D and that fixed the problem of the tps voltage not matching the position of the throttle and i am reading a min. of 0.23v at closed throttle and open throttle is reading 2.57v...what has happned to 2.39 volts that are not shown in the TPS?
 

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Brah.
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7,484 Posts
Discussion Starter #18
fixed the issue with the TPS not reading the full 5v by replacing the MAP sensor.
 

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fixed the issue with the TPS not reading the full 5v by replacing the MAP sensor.
Great news Noah! I learned that from experience that AEM can only recognize certain MAP sensors. Troubleshooting is not fun but hang in there & now get that thing tuned by someone that really knows how to tune the AEM and you'll know what IRTB's are all about. Jdmeg2 and Moto_Bruce Thank You for helping out!!!

Jimmy
FujiRacing
 
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