4age ITB and Cam starting issue.

Road 2 roku
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4age ITB and Cam starting issue.

Postby Road 2 roku » Wed Jan 06, 2016 3:09 pm

Hello, I recently bought a GTS from California and drove it back to Arizona without a problem. Now that Im in Arizona the car won't start up. The car has a standalone AEM EMS series 1 and is running extremely rich since it needs a tune. It also has Hks 272 cams with 8.35 lift and I believe 20v ITB's. The car has spark and fuel and I am unsure what else to check to get it started. Im going to check the timing soon, but wanted to also figure out how the ITBs are measuring the air flow. Any suggestions or advise will be greatly appreciated.

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aceforever
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4age ITB and Cam starting issue.

Postby aceforever » Wed Jan 06, 2016 6:01 pm

There are a few ways ECUs measure airflow for the purpose of looking up fuel injector timings from a fuel map. MAF(usually used in tandem with a plenum to measure how much air was drawn in by the engine) sensor, MAP(measures air pressure created between throttle plate and engine) sensor, or Throttle Position Sensor(how open a throttle plate is)

Since you have an aftermarket ECU it could be any of those.

Common ways of tuning ITBs are TPS and MAP.

Road 2 roku
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Re: 4age ITB and Cam starting issue.

Postby Road 2 roku » Wed Jan 06, 2016 11:45 pm

Thanks for the quick reply.

Yeah the ecu is using a tps sensor, but I don't think the itbs have a maf or map sensor. I think the ecu is running on speed density to operate with the itbs. Is there a way to put a maf or map with open ITBs?

aceforever
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Re: 4age ITB and Cam starting issue.

Postby aceforever » Thu Jan 07, 2016 12:15 am

TPS sensor is usually the preferred way of tuning ITBs due to not enough air vacuum making its way to the MAP sensor at near wide open throttle. So thus it's harder to tune near WOT (I'm currently facing this with my ITB setup)
Usually TPS signal is used in conjunction with a barometer (using a MAP sensor not connected, open air, or some other sensor) to offset fuel timings at different altitudes (as you may know, higher altitudes require less fuel at same throttle positions).

The benefit with using MAP as engine load is that it accounts for change in elevation because air pressure reduces at higher altitude.

Anyways, for getting MAP sensor to work, you'll need to work out some plumbing. Each intake runner must connect up to a vacuum box, this will average out the vacuum and this vacuum box is then connected to a MAP sensor. If you have a hooked up Brake Booster, you can follow where the vacuum hose goes to to see if you can find the vacuum box. Keep in mind that BT/ST intake manifolds might have the vacuum box built in. (my setup is a bit different)

For MAF to work, you'll need a plenum. No open ITBs unfortunately. It sits somewhere between the air filter and plenum tubing.

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aceforever
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Re: 4age ITB and Cam starting issue.

Postby aceforever » Thu Jan 07, 2016 12:19 am

Your original post is about starting issues, have you checked to make sure the basic stuff? Like you're getting fuel and timing? From my experience, that's what I worked on to get my engine started.

What happens when you try to start the engine?

totta crolla
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Re: 4age ITB and Cam starting issue.

Postby totta crolla » Thu Jan 07, 2016 9:30 am

Are you able to connect the ecu to a computer ?

Deuce Cam
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Re: 4age ITB and Cam starting issue.

Postby Deuce Cam » Thu Jan 07, 2016 11:43 am

Where in AZ? Shameless plug: check out azt.org if you haven't already.

I don't have any technical advice, but if you're in the PHX area UMS is a very respectable shop and they know AEM ecu's.

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Re: 4age ITB and Cam starting issue.

Postby yoshimitsuspeed » Thu Jan 07, 2016 12:11 pm

You really have about 3 options right now.
1. Either dive in the deep end and learn everything about your setup.
2. Pay someone else, likely a lot of money to do the same.
3. Buy a car that is closer to stock and modify it to meet your needs and learn along the way.

If you are going to do 1 you will need to start doing a lot of research. Start reading up on the AEM unit you have.
If you don't have a wideband you will need one.
Pull the plugs and find out if the motor is flooding or leaning out or what.
Find out if the ECU uses an 02 sensor and uses closed loop learning. This is best and would have adjusted for elevation changes as a stock ECU will.
If you don't have MAP or 02 you might as well be running carbs. It's those things that make EFI superior.
Personally I would always run MAP on any setup and it shouldn't be hard to get a good reading on ITBs but you do need to tie all cyls together and it can sometimes help to add a reservoir to help absorb the vibration of the intake pulses.

Road 2 roku
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Re: 4age ITB and Cam starting issue.

Postby Road 2 roku » Thu Jan 07, 2016 11:42 pm

ace forever
I think your right, the car has no way to measure the air and is set to speed density, the change in elevation is causing the car to run more rich. I'm going to attempt to adjust the tune tomorrow to see if I account for the change in elevation. I'll probably need to reduce the fuel map by %5 to get the car to start. But if there still is no start I will definitely take your suggestion and install some sort of barometer. I was also looking at one of those MAP sensors setups where the hoses connect to the ITB's, but if possible I would like to keep the engine bay with as minimal hoses as possible. However still a valid option if nothing else works.

Yeah I checked to see if there was fuel and spark. I added an adjustable fuel pressure regulator and when the car cranks the gauge goes to 40 psi after adjustment, but slowly goes down to zero. (approximately 1-2 minutes after cranking and hearing fuel pump prime). Is the fuel gauge supposed to hold fuel pressure even if the car doesn't start? I recently replaced the spark plugs and used a spark plug light to make sure I am getting spark. I am unsure on the timing since the car also has adjustable cam gears. My plan is to try and slightly adjusting the fuel map to compensate for the elevation change and if that doesn't work a friend and I are going to set everything to top dead center and try to make sure everything is in its proper rotation.

When I try to start the engine it just cranks and sometimes gives puffs of gas out of the ITB's.

totta crolla
I am able to connect the computer to communicate with the ecu.

Deuce Cam
I live int Tucson, lol I don't think Aids information will help me in getting my car running. Cool, I'll probably go to a local shop called PSI here in Tucson as an ultimatum.

yoshimitsuspeed
I'm probably going to go off the deep end, since I got a great deal on a 87 GTS Hatch. If these cars didn't have takumi tax, weren't all rusted, difficult to find and not mostly drifted I probably would have went the stock route if given the option.
But since I am stuck, Ill probably try to restore it to something closer to stock. I have read up on the AEM EMS series 1 ecu, but since its an older ecu its harder to find technical support for it since aem doesn't support it anymore. I'm in the process of reading the manual, but if you have any other sources I would be glad to check it out.

The car does have an aem afr and an 02 sensor, but I am not sure if it uses closed loop learning.

Thanks again everyone for the help

yoshimitsuspeed
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Re: 4age ITB and Cam starting issue.

Postby yoshimitsuspeed » Fri Jan 08, 2016 12:25 am

Okay so the wideband is hooked up with a gauge so you can monitor AFRs right?
Just want to make sure you don't do any tuning without a way to monitor the effects.
That's not an issue until you get it started but thought for once you do. One thing I like to do when tuning cold start is hook the wideband to an external power source so it doesn't reboot every time you try to start it and this way you can monitor AFRs as soon as the car fires.
but first you will need to get it to fire. This is going to take basic diagnostics first. Check for spark, check for fuel, check the plugs etc. Try to find out what it's not getting. Don't let your suspicions prevent you from an otherwise obvious discovery like the crank position sensor fell out, or the distributor spun all the way one way or the coil wire came off or something like that. It is quite possible this is related to altitude but it's about as possible it could be any number of other things. Going up a few thousand feet really shouldn't be enough to stop it from starting unless it was already borderline too rich to begin with.

One other note, speed density generally describes a setup using map and intake temp to estimate volumetric airflow. I'm not sure what the term would be for your setup but unless you drive at the same altitude in the same weather every time you go out it's definitely far from ideal. If I had to prioritize items on a car I would have to put things that make the motor and ECU work better at the top. If I had to choose between MAP/intake temp sensors and window cranks the cranks would have to go. I understand wanting to keep it simple but IMO the key purpose of an engine bay should be housing a happy engine.

totta crolla
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Re: 4age ITB and Cam starting issue.

Postby totta crolla » Fri Jan 08, 2016 11:21 am

Once connected to the ecu check the 'stat sync' status when trying to start the engine.

Deuce Cam
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Re: 4age ITB and Cam starting issue.

Postby Deuce Cam » Fri Jan 08, 2016 4:32 pm


Road 2 roku
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Re: 4age ITB and Cam starting issue.

Postby Road 2 roku » Sat Jan 09, 2016 8:01 pm

yeah the AFR is all connected and set up. I have air, fuel and spark. Still haven't checked timing. I'm going to take your advice and go over the car again and make sure everything is connected up.

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