map smallport 4age not starting / running rich

[Jeonsah]

Hey guys, Here is my setup:

1. Completely rebuilt smallport 16v 4age in my AE86 that i am just not trying to get on the road for the first time.
2. jdm AE92 map harness & auto ECU.
3. smallport intake manifold with the ends cut and swapped around.
4. I removed all of the unnecessary things from the harness. The harness has not been loomed yet, to help ease in diagnosing the engine if there were any issues.
5. Innovate wideband LC-1

So here is what has happened:
Got the car running with no smoking. Had a huge vacuum leak from the pcv internal galley to the throttle body. I fixed the vacuum leak and got the car running around 1100rpm. I tried to set the timing and couldnt not get the notch on the crank pulley be lower then 20deg on the plastic cover. I had the distributor turned all the way towards the firewall to get the timing where it was at. I decided to leave it there and try and do a test run on the car the following morning. The next morning I go out and could not start the car. It has been 2 weeks since then and I am completely stumped as to what the problem could be. I have checked the error codes and here is what it has told me:

Errors Codes:

1. First time it said: 24,31,51
2. After tinkering with things: 22, 24, 31, 51
3. After tinkering and replacing map sensor: 24, 31,41

Here is the list of things I have done:

1. jumped the fuel pump - did not run
2. disconnected cold start switch(brown connector) - did not run
3. swapped around copper and platinum pugs - did not run
4. Checked all fuses and relays - everything is fine
5. Blocked off all vacuum leaks in the intake with bolts
6. Deleted IACV with KSD block off plate
7. Checked compression - all four cylinders at 150psi @ 7000ft above sea level
8. Checked engine harness - seems good. No shorts or breaks in any wires
9. Have spark at coil, dizzy, plugs & wires
10. replaced FPR - no difference
11. disconnected cold start (black) - no start
12. Opened the ECU - no leaky capacitors. Inside looks mint
13. Brand new bosh O2 sensor
14. getting fuel on the return line


TPS:
1. disconnected tps - did not run
2. tps is grounded through E2
3. tps gets 5 volts with key ON
4. Blue wire on tps has continuity
5. Red wire on tps has continuity
6. Swapped tps made no difference

IAT:
1. swapped iat's - no difference
2. THA wire to ecu has continuity
3. iat is grounded through E2

MAP:
1. map grounded through E2
2. map getting 5 volts with key ON
3. PIM signal to ecu has continuity
4. replaced map sensor

ECT:
1. disconnected - no difference
2. sensor is grounded through E2
3. continuity on THW signal from connector to ecu
4. read 2.9k Ohms

Injectors:
1. getting 12 volts on black/red wires with key ON
2. getting 12 volts with green/red/yel wires with key ON

So when I pulled the spark plugs, they were wet black. And the car is smoking out the exhaust and the wideband is saying a reading between 9 and 10.7. So its running extremely rich. So I got pissed off and decided to disconnect the brake booster and induce a vacuum leak. Car started right up and went to 2000rpm and kept running. Soon as I blocked it off, it died. If I open the idle screw a lot, the car will start and run (doesnt run great and it shakes a lot). Spark plugs were still wet black.

At this point I have no idea to do. I think the the car is cursed because I have owned it for 4 years and mabe have put only 1 month of driving on it. It has fought me every step. I am having a hard time believing my ECU died overnight.

So yea, does anyone have any input for me?

*sigh*

thanks

[jondee86]

MAP sensored AE92 smallport had this airbox...



The little blue plug belongs to a PWM controlled idleup valve embedded in
the side of the airbox. The valve lets air into the intake manifold via the
skinny tube you see heading off to the left. That tube connects to one of
the small metal tubes on top of the throttle body.

Your engine is obviously starved for air... first problem. So open up one of
the little tubes on top of the throttlebody and leave it open for now. You
need to get the engine to stay running, and if it idles at 2000 rpm for now,
don't sweat it. The engine will be loaded up with unburned gas, so you need
to run it long enough to get some heat into the engine and burn up that gas.

Once it is up to temp see what your AFR settles at... you could have a MAP
sensor problem as well if the engine is still running way rich. Then back the
idle down to around 900 rpm by closing down the idle screw, and check
your timing. Around 17 deg without jumping the diagnostic plug is good.

Cheers... jondee86

[Jeonsah]

Thanks for the reply Jondee. After reading your post and thinking about a few things I see what the problem is. All air that gets past the butterfly for the engine to idle has been closed. So therefore the engine cant run. It would make sense that the computer would throw a map sensor error code since the sensor is not getting any vacuum. I guess it went over my head that idle screw adjusts a hole to let air past the butterfly(I thought it moved the butterfly valve) and that there is no idle help from the ECU.

Currently, I am unable to work on the car but I have the spark plugs pulled out so hopefully some of the fuel in the cylinders will evaporate. I will have more time to work on it this weekend. So I will keep you updated on what happens.

I plan on opening up one of the vacuum tubes on top of the throttle body. I may have to open 1 or 2 for now. The only thing I am worried about is after messing with the idle screw and closing all the vacuum ports, is whether or not the the actual hole in the throttle body for the idle screw is large enough to accommodate the amount of air the engine will need to idle. If it is not enough, what should I do to fix this issue? or will it more than likely be enough.

Also, I have an Apexi SAFC2 to control the fuel. I plan on using that once I get the timing dialed in on the engine and if the A/F ratio is off.

[jondee86]

The idle air by-pass screw plus one of the little tubes on top of the
throttlebody should pass all the air you need for idle. You may not even
need the little tube if you open the idle air screw up. The engine requires
surprisingly little air to idle, as you discovered when you opened up the
brake booster hose.

Cheers... jondee86

[morgan]

Sounds like the dist is off a tooth if youre unable to dial it in closer and its turned all the way

[Rogue-AE95]

That tube connects to one of the small metal tubes on top of the throttle body.

A quick aside question (might help Jeonsah). I have a JDM throttle body I was going to use for my build. I'm guessing the port you're talking about is the larger one of the two, with the hole that leads behind the butterfly plate?





If I use this for my build, without a JDM airbox or a stock Toyota ECU, would I need to run a hose from that connection to the intake (pre-TB)? I thought idle was achieved through the port visible in my second pic, on the right just under one of the four mounting holes, and of course through the idle adjustment.

I'm also curious to know what that port labeled "C" is for. It leads to a pin hole in the TB just in front of the butterfly plate in the closed position.

[jondee86]

The 4AGE throttlebody has a heap of variations according to the market for
which the car was built. Offhand I don't know what the letters stand for, but
these are the ports you can expect to find in most of the 16V 4AGE variants...
1. One large port from inside the front of the TB to the back of the TB behind
the butterfly. This one exits bottom left side of your second pic, and is for
the thermostatic idle-up valve.
2. One large port as above but not sure where it exits. This one is for the
idle air by-pass.
3. One large port that enters the throttlebody from the manifold side under
the top fixing bolt holes, and exits in front of the butterfly. RWD have it on
the RH side and FWD have it on the LH side. This is the exit port for the
cam cover vent. Some TB have the hole on both sides, but only one works
as the manifold is blank one side.
4. Small metal tube on top for the charcoal canister. This one vents in front
of the butterfly and is probably marked "C".
5. Small metal tube for the electrical load idle-up solenoid. This one exits
behind the butterfly somewhere.
6. Slightly larger metal tube for the A/C electrical idle-up valve. Also exits
behind the butterfly.
7. USDM have connections for EGR controls and other weird stuff
8. Underneath are larger connections for the P/S idle-up

If you are connecting an idle-up valve you just need to connect to any
tube that ends up behind the throttle butterfly.

Cheers... jondee86

[Jeonsah]

Alright so I got to work on the car again. Here is what happened:

Opened up the idle air screw (a huge amount) and all of the vacuum ports at the top of the throttle body. Engine started and only got up to 1100 rpm and was chugging and throwing the same codes: 24, 31, 51. My wideband is telling me it is running supper super rich at 9's and 10's. So I just turned off the engine because I didnt want to do any damage. I tried swapping out multiple map sensors and they made no difference. Also when the engine was running, I pulled the connectors for the TPS and the MAP and it didnt make a difference on the engine. If I pull the brake booster hose, the engine will go to a higher rpm.

I also checked the vacuum line to the map and it seems that the engine is surging a small amount because the vacuum is not constant. So I pulled a couple fuses in the engine fuse box so I could reset the ECU. Started the engine, and still ran into the same issues and codes.

So does anyone know what I should be looking at next?

I will be double checking the wiring for the TPS and MAP and all the pinouts for the ECU. Otherwise, from my problems listed above I think the following:

- Bad ECU or TPS/MAP circuit
- Throttlebody issue since the vacuum ports dont affect idle rpm.

[Jeonsah]

Sounds like the dist is off a tooth if youre unable to dial it in closer and its turned all the way

Hey morgan, Ive thrown in the dizzy quite a few times with it lined up different and it didnt change anything. I lined up the dot on the gear with the hole (if you know what im talking about lol).

[morgan]

Its been a while but i remember, lol. Just sou ds like its off a tooth if its all the way to the right and still not in spec

[Jeonsah]

Well when the engine was running that is when I had the dizzy turned all the way. Since then I have put it in multiple times with the tooth readjusted. Right now it starts with the distributor dead center and not turned at all but I have not been able to try to set the timing again. I will try turning it some more to see what happens. Ill post up in a bit what happens.

[jondee86]

When the engine is running, can you rev it up normally with the throttle ?
And if you rev it up, does it run smoothly or cough and fart ?
If you raise the revs to (say) 3000 and hold there, what is the AFR ?
Have you ever had the engine up to normal operating temperature ?

The ignition advance jumps up pretty quickly once the revs move away
from idle (850-900rpm). Without having the diagnostic plug jumped, you
would have 16-17 deg at idle, so you could have 20 deg or more at 1100rpm.
To set the timing correctly you need to get the ECU into diagnostic mode
and set the base timing to 10 deg. You can do that once you get some of
that excess fuel out of the engine.

What injectors are you running ? Are you sure they are not GZE injectors
or something from a Supra ?

Cheers... jondee86

[Jeonsah]

Alright so I worked on it some more and it looks like Morgan was right (THANK YOU MORGAN!). I messed with the distributor a bit and figured out where it wanted to be after trial and error. Apparently not lining it up is the right way to do it lol. So after the distributor was in the engine started up right away with less chugging. All of the codes went away too (I have no idea why a distributor would cause a iat, map, and tps error code). But the engine runs and I can actually mess with the idle now. I used some starter fluid to find vacuum leaks. It had one from the no. 1 injector (even though its a new seal). So I threw a new seal on it. I will mess with it more tomorrow.

When the engine ran before, I had to mess with the spark plugs. The only weird thing that it is still doing is skipping like the spark plug gaps are off. Basically I bought some NGK coppers for a 91 corolla GTS and it ran like crap with the factory spec gap 0.032". So then I tried them at largeport gap of 0.042" and it ran better. Then I went and got some platinum ngk's for a stock AE86 largeport and it skipped less. However, now the engine is skipping even with those new spark plugs in it....

The engine is bored over to the next size from factory. Would this have any affect on the spark plug gap needed?

Jondee:
It is running the factory Geo Prism gsi injectors that it came with.
When the engine was idling (with the injector vacuum leak) it was around 15.3 (lean now) but kept jumping all over from 14.7 to 16.2 or so. Mostly stayed in the low 15's.

I did not get a chance to check the revving of the engine. However, I can tell that it is somewhat responsive now. I got the engine up to normal temp for a little bit while I was spraying areas with starter fluid. Once I hit the injector, the revs dropped about 300 rpm. The other weird thing is that when it is running, if I have the idle screw completely closed, it will NOT die. Also, I did not rev the engine at 3000rpm and check the afr. I will do that and try to set the timing tomorrow.

If you have any ideas about anything please post. Any help is welcome.

Thank you for the help guys, Im really happy to have some ppl who can help me out.

[jondee86]

Hey... sounds like you are on to it now

AFR's can be on the rich side when the engine first starts, as the
ECU will put extra fuel in when the engine is cold. But anywhere in
the 14-15-16 range on a fully warmed engine at idle is fine. Later
when you get some load on the engine, they should drop into the
13-14 range for normal driving... lower when you get on it !!

I have never checked to see if the idle air by-pass screw actually
fully closes the by-pass or not. It may not, since the engine should
always need some air. Try closing the by-pass port with your finger
and see if it kills the engine.

Cheers... jondee86

[Jeonsah]

So after messing with the car, I still cannot get the idle down past 1200rpm. I sprayed all over the intake manifold with starter fluid and it made no difference. I am pretty sure I have found all of the vacuum leaks now unless there is something going on with the throttle body. Since the car was idling at 1200 rpm, I was not able to adjust the timing with a light. So I just tuned it by ear and found where it was most happy. I took it for a test drive and found a few more bugs.

The main bug that I have to fix is when I shut my car door, it sometimes would kill the engine..... POS
After the car dies, it throws the same original codes 24,31,41,51. So Im assuming it has to do with the distributor. If i pulled the engine and efi fuses, it let me start it again and it ran normal. Then after some driving, pulling the fuses wouldnt work anymore. With the harness swap, I had to extend the distributor wires since I was using a fwd harness. From the distributor there is about 6 inches where the wires are not shielded. Would this be an issue? I plan on redoing the distributor wires and see what happens and also trying to find some internal parts for my JDM distributor.

Does anyone have any ideas of what I should look for?
I checked all electrical connects and jiggled every piece I could while the car was running to see if it would die. Nothing would cause it to.

Lastly, the engine AFR's look good when I got to drive it a couple times around the block. When it was idling at 1200 rpm the AFR would be very close to 14.7. Then when I would give it more throttle it would get richer. The engine rev'd nicely and did not present any driveability problems.

Also, I gapped the copper plugs .004" larger from 0.042" to 0.046" and the engine runs smooth now.

[jondee86]

Could be a grounding issue. Did you double check that you have the
ECU grounds bolted down ? Those are the 3 or 4 brown wires that are
fixed to a single brass ring connector, and bolt down under the injector
harness at the rear of the head. Easy one to miss.

Cheers... jondee86

[Jeonsah]

Hmm. Here are my grounds:

1. 4 brown wire one on top of intake manifold
2. Ground wire from intake to body
3. Ground wire from head to body
4. Ground wire from engine bay fuse box
5. Ground wire from transmission
6. Ground wire from steering column

I tried turning the distributor while starting it and it did not make a difference. Would the shielded wire ground touching some part of the engine or firewall cause this issuse?

Also, when the idle screw is closed, with the hole blocked with my finger, the engine still ran. So I still may have some kind of vacuum leak somewhere or the throttle body just lets in a lot of air still.

[Jeonsah]

Just for future reference if anyone runs into the same issue. This problem was solved. The ecu connector was bad. It was allowing the wires to move too much inside the connector.