WojtekG

I have the following problem to study and hopefully someone already has solved similar one.

My engine is LS/VTEC (B18B1+B16A2) with Turbo.
Problem is the following:
1. Engine when warm has not stable idle, fluctuating between 600 and 900. If I do not rev up the engine to prevent it from stalling then engine shuts down.
2. After that I can usually start the engine right away, but then engine usually stalls quite soon after pressing the throttle pedal. Sometimes I need to wait 1-3 minutes before engine can be started.

Additional information:
1. Engine starts without any problems when cold and the revs are dropping slowly to the proper level when engine is getting warmer and warmer.
2. Temperature gauge usually stops at 1/3. I do not remmeber If I ever managed to get this engine warmer.
3. I bleeded the coolant after I recently replaced the ECT sensor, because I was suspecting it was causing before problems with starting engine on warm. Before this replacement I didn't have the problem with engine stalling, but sometimes idle was not stable as now.
4. The heater works ok, so I assume the bleeding was successful. Honestly I do not know anyway if I need to bleed the coolant after replacing the ECT.
5. When idle is not stable and dropping to around 500, then just touching the throttle pedal can cause engine to stall. The same usually happens at this low idle, when I try to rev it higher and then suddenly depress the pedal. Revs drop down and stalls.
6. ECU is not showing any error codes.

What I did so far:
1. Eliminate the problem with cold welds in the main relay.
2. Cleaned IAC valve (I hope well enough)

Any other ideas? I would like to solve this puzzle before making decision of replacing tons of parts that can be theoretically responsible for this bad engine stalling.

Any suggestions will be appreciated.

WojtekG

It's a pitty nobody seems to be able to help me with this problem. But I've do few things so I give you an update:.
I replaced the o-rings for IAC valve and cleaned the throttle body. Then I adjusted the throttle cable. The result is that I have good, quite stable idle, but one problem remain that actually is not allowing me to drive the car. The problem is that when I'm slightly depressing the throttle pedal or move gently throttle directly, than engine almost stalls and is not allowing to increase revs really. Feels like choking. Can it be the problem with throttle body itself? It would be weird.

I hope someone may have some idea this time.

Thanks in advance.

WojtekG

Continuing my conversation with myself (-; I've calibrated TPS according to service manual and after assembling back throttle body with intake manifold engins stalls and dies just after starting up. It starts, revving up to approx 1800 and after fe seconds is stalling and dying. It can be keep on by depressing the throttle pedal but only if I do it quite quickly, beause slow depressing makes engine to chokes and stalls to die.

Anybody help? Please.

wunfstgsr

What ems are you using?

You need to get the ecu chipped if you haven't already with something you can datalog with, get a Hondata S300 or similar and see what your ECT temps are when it reaches OP temp. Im willing to bet your ECT sensor is still bad or has a bad connection. Soon as the engine reaches OP temp the ECT sensors is no longer sending the right signal and the ECU will not be able to compensate to idle the engine correctly. It also sounds like you have a tuning issue, is this ecu on any type of Base map at least or are you actually crazy enough to try driving the car on a stock ecu of any sort?

tamboo

you can test the resistance on the ect sensor at diff temps
to see if it's up to spec:
temp (degrees f) resistance (k-ohms)
-4 12
32 5
68 2
104 1
175 0.5
212 0.4
248 0.2

same table works for intake air temp sensor too.
from the haynes manual, not in helm iirc.
if ect sensor is bad try to swap quickly to avoid
air in system. it was a b*tch to bleed mine as my coolant
block bolt is stuck and rounded off. finally had to buy
the lisle funnel set which eventually did the trick.

WojtekG

Many thanks for Your responses.
I'm using Greddy e-Manage Blue as the piggy back ECU and the car was running OK for very long time, so I assume the source of the problems are not related with it. But it doesn't have logging of ECT I believe. It was installed and tuned alike 12 years ago, so I do not remember how it was done really (-;

I will try to test resistance of ECT as you are suggesting, maybe even first by swapping back the one that I replaced. In addition what I thought overnight was that the problems were changing their nature every time I was disassembling and assembling back throttle body. I've got the feeling that there might be the issue with the connection of MAP sensor as it's being disconnected and connected during the throttle body removal or there is a problem with Throttle body itself (but I do not know if the throttle body can cause such problems).

BTW, forgive me silly question, but at what temperature the fan shall start up. I've got impression that cooling fan in may car never starts, but engine keeps stable operation temperature. Is it the influence of turbo intercooler that engine can cool itself without swithing on the cooling fan?

WojtekG

Next day, new facts. I've conducted MAP sensor diagnostics as specified in service manual and found out that it didn't pass one of them (see picture WHT/YEL is sensor signal and GRN/WHT is ground). Connector is fine, because I check the voltage on the wire after the connector to be sure. If the service manual doesn't lie than I need to check the whole wire going from MAP sensor to eManage and wire going from eManage to ECU that send air pressure information. Honestly I thought there would be no voltage when there is only atmospheric pressure on MAP sensor (or sensor disconnected), but it seems that there shall be 5V. Do I understand correctly the meaning of this test, that my wires failed?

Michael Jasso

Hello there I was just wondering what your next steps are for figuring out this problem? I have a 90 acura integra b18a1 all stock automatic and I'm having the same problem. She turns on beautifully but as soon as I put it in drive the engine begins to idle super low and any touch of the pedal kills it, but as soon as I put it In park it comes back to normal idle.

I cleaned the iacv
I adjusted the fitv
New tps
I love my car so any suggestions would greatly appreciated.

WojtekG

Well, I have some progres in investigation, but so far haven't found the real solution.
So far I did the following:
1. Cleaned IACV
2. Cleaned Throttle Body
3. Calibrated TPS
4. Changed the fuel filter - because I thought that there was lot of trash cummulated that was blocking fuel pressure
5. Adjusted Throttle cable up to specs
6. Replaced ECT (engine coolant temperature) sensor
7. Verified that MAP sensor was working fine (by replacing it with another one from my friend). My post above with MAP sensor test was faulty, sorry for that, my mistake.
8. Verified that ECU works ok

So at this moment when engine is cold, that it starts with some hesitation, ie. not at first cranking, but after cranking for the second time and then it revs for a second up to 1800 and then dies, unless I play with throttle. Today I managed to keep it up and running until it got the operating temperature (even the radiator fan started to work) and when warm engine is not dying, having idle at about 800 rpms. I haven't drive it yet, because I'm afraid of having problems on the street, but I will try.

Nevertheless recent status let me think that there is definately some problem with the fuel supply when the engine is cold or with spark. I exclude the problems with air supply at this moment, as also you said that you adjusted FITV and problem is still there.

What I'm planning to do is the following in the following order:
1. To remove again the air from the cooling system (just in case).

2. To test somehow (using probably some youtube guide) the rotor and distributor cap, because I've read somewhere that these elements corroded may cause the symptoms we have.

3. To check the fuel pressure at the fuel filter and on the fuel pressure regulator (unfortunately I will need to take it to the workshop as I do not have the fuel pressure manometr). If the fuel pressure is below the specs on idle (43 psi If I remember) that it may mean that there clogged fuel line or fuel pump is not working properly. But on the other hand if it's the case than why when engine is warm the problem seems to disappear?

4. I will check if the timing belt is in the right position. It was changed recently and maybe due to the mistake in workshop it's shifted by 1 step that can cause many strange looking problems with ignition and idling.

5. If points 1-4 do not give me answer than I will take the throttle body for regeneration to the workshop as this can also be the source of the problem as I read somewhere. But on the other hand the fact that problem is appearing when cold is making me doubt that throttle body itself is causing the problem.

I need to replace the PCV valve, but I do not think this is the source of the problem because I think I broke this valve when trying to replace it, after I started to have this problem with engine
already.

Could You please let me know when You've noticed this problem (after some repairs or something) and if you have this problem always or only or cold or warm? If always than I would check the throttle body as I think with AT you have two throttle cables in there that may need adjustment.

tony_2018

how is the e-management cabled in?

WojtekG

I've double checked emanage connection and wiring and it looks fine. It's done according to the user manual. There were no modifications or any adjustments done in this respect in the meantime and car was running great with it for long time, so I do not suspect e-manage as a troublemaker this time.

wunfstgsr

Check the IAT sensor!

Michael Jasso

Awesome im gonna go ahead and do 1, 3, and swap out the fitv, iacv, catalytic converter just in cases( ill let you know if any of this makes a difference). what i did do was redo the timing with a new tensioner, new/ old distributor off a working vehicle. it idles better but Its weird because the car decides to die out when i simply put it in drive, so it does it all the time warm or cold. While its in park it idles beautifully which is what has me stumped. A few more things i noticed is that when it does begin to die out as i shift it in drive my cluster and headlights begin to dim in and out. i dont know if thats because shes just losing power or bad ground( i did swap the old ground wires with new ones and cleaned the post on the transmission and under the battery). also i added a ground wire to my main relay and she seem to start up with a better kick in park but as soon as i shift it in drive it begins to idle super low and dies. same problem. Does the shift lock affect any of this in any way? I do have to insert the key in order to shift the vehicle. Thanks for the response really motivated me to keep going.