View Full Version : 3sgte hesitate

01-03-2013, 10:17 PM

Start of by saying that my english is crap.

Drove my car for the first time in 5 years ( been rebuilding it ) and two things happens

To know is that the engine is prestarted prior to this, runs fine in the car sitting in the garage.

Take it out for a drive and...

Fuelpressure drops. I run a Walbro 255 pump, an6 feed and return line, st165 injectors with rail and a aftermarket regulator. When i started the engine 2 weeks ago in the garage i set the pressure and it was stable but now after driving a while it drops. From 2.7 kg idle no vakuum to 1.8 kg no vakuum. Dirt in the tank? fuel filter is a orginal but been with me a while, time to change?
When i rev the engine to about 2000-2500 revs

Secon problem

The car runs fine upp til running temp and 1 drive about 20 min after it is at running temp. I park the car about 20-30 min and starts it and it goes like crap. Fuel pressure was about 2-2,2 kg. No power, no will to rev, If i put down the accelerator fast it almost stalls. If i press the accelerator gentley ant slowly rise the revs it works. Some stutter and when i release the accelerator it has a ide somewhere arunde 550-650 rpm. I slowly press accelerator and let the car "rest" at 2500-3000 rpm, drop the accelerator and it feels better but not perfect. still have to rev to 3000-3500 rpm and almost drop the clutch to get it to drive from the outside of the garage to get in inside.

Now this is a homebuild engine with alot of different parts in it.

St165 block
st165 crank
JE pistons
Eagle Rods
st182 head and st185 cams, org valves
comp is 9,2:1
st185 ECU and full harness and all that stuff
ct26 + org intercooler ( a2a ontop )
mr2 wateroutlet with st185 sensors and a homebuild radiator.
org inlet manifold + org throttlebody
T-vis and homebuild adapter plate between st182 head and st185 intake manifold
list goes on

The car drives prefekt untill i park it, pulls strong, eagar to rev and feels like it should

it give me a clean health on the onboard failsensor system om the ecu, i have checked before and after problem and no enginelight comes on while problem occures.

So could it be heatsoak from intercooler?

Hotspot in the coolingsystem fucking upp som sensor?

Something with cold start injector ( runs fine from cold -2deg cel and to running temp, could there be a problem when i start the car and water temp says 40-50 deg cel )

As i run a st182 head it does not support the return of exhaust gas to be burned again, the entry on the right side of the manifold has been sealed, could it be som problem with this ?

Hope you understand my english. Have you guys and girls have heard or had this problem.


The Captain
01-04-2013, 10:58 AM
Change the fuel filter?
I don't trust anything but OEM fuel pumps.
I'd pull the pump and check the tank for rust first. You didn't post where you live, so we have no idea what your climate is.

01-04-2013, 02:10 PM

Live in sweden.

Will change filter and se if it does something, perhaps the membrane in regulator could be problem to.

I thing that problem 2 is not due to the pump pressure. I have 2 bar with vakuum just as manual says and still problem with no power and no eager to rev.

But change the filter i have to do anyway so i`ll start there


The Captain
01-04-2013, 02:46 PM
Pulling the fuel pump is easy. I'd check the filter on it too.

01-04-2013, 03:12 PM

I`ll pull the pump too.

I have read that som 3sgte owner have problems with hesitating engines while they are cold and that the AFM is the source, anything you have heard?


01-04-2013, 05:24 PM
I would definitely swap the filter first and see where it goes from there.

01-04-2013, 05:40 PM
Ok, so filter is on its way to me. I will start the car and se if the problem is still here now that is completly cold
will be back and say how it went after filterchange


01-05-2013, 03:36 AM
Fuel pressure needs to be checked under load. Free revving the engine doesn't take much.

01-05-2013, 11:17 AM
I tested it under no vakuum as the manual said and set it to that. The manual only tells what pressure it want at idle with and without vakuum. Nothing at load. The problem is that as i`m running a different comp than org i will be seeing a little different when under load. Your boost/vakuum gauges will read little different from mine. Org comp is 8,8:1 i believe, my is 9,2:1. Does anybody know how much fuelpressure there is when the ECU bypasses the resistor and run the pump at full? I don`t find this anywhere in the manual. I havent messaured the resistans yet so i dont know how much it will pull from the pump.

What pressure do you have MrWOT and at what boostpressure?


01-05-2013, 09:08 PM
There is the same amount of pressure at low pump speed as there is at high speed. Pressure is determined by the rail regulator, not the pump, the pump just kicks into high speed to keep up volume so pressure doesn't drop.

You should have ~3bar at idle, and fuel pressure should rise in 1:1 proportion with boost pressure.

01-06-2013, 08:36 PM
So to check the pressure under load as you said is just to check if the fuelpump is upp to the task of delevering fuel at at higher demand? I was just wondering as my vakuum at idle is not the 60 kpa org gen2 3sgte should have. This should affect my regulator aswell.

Anyway, problem nr 1 is fixed. 2 things. 1 small bend of fuelline ( me being a idiot ), and alot of shit in filter. i ran with shittyfilter and straighten bend and i went from 1.8 no vakuum to about 2.2. then i changed the filter and i got 2.6 bar wiht no vakuum.

But problem nr 2 is still here. No eager to rev and powerless when i drive it upp to running temp and then let it rest for a while. Start it up and problem is there.

I am thing coolstart or temp reader things my engine is to hot and dump alot of extra fuel

Any thougts?


01-06-2013, 09:36 PM
Correct, checks if pump can keep up with demand. You should have ~3bar at idle.

Still sounds like a fuel starvation issue to me. Pull vac line off fuel pressure regulator and make sure it's not leaking fuel past the diaphragm. Be prepared to change the pump, if the filter was that old guarantee the pump is too.

High ECT (engine coolant temp) won't make the computer go nuts, it's somewhere else.

01-06-2013, 10:00 PM
Ok, then i understand.
I was thinking the same about the pump. The pump is new whit only about 3 hours running totally but then again with alot of shit in it would not work good anyway, just thinking there would be more grinding sound to it.

i will pull vakuum at pressure regulatar to se if there is a leak.

But if the car runs fine for about 40 minutes, i have it running till it hits running temp and then 20-30 minutes after this, running the car up and down a hill mostly, i find that a lot of problems appears when it is under load and a hill works for me. And there is no problem with the car when i run it. I turn it of and wait about 20-40 minutes and then the problem appers.

When i run the car with the problem in the garage by holding the revs about 3000 rps for a while it gets better

As long as i run the car it works. then it stops so i dont thing its fuel starvation. I have a wideband but it is not hooked up yet, would it work just below the first catalysator? this is the first place i can weld a bung to fit it into. Would be nice to know what a/f i am running when the problem occures


01-07-2013, 12:48 AM
Weld the wideband bung as close to the head as you can get on the leanest cylinder. Without aftermarket EMS you can only tune to the leanest cylinder anyway.

How long does it take the problem to go away when you drive it?

01-07-2013, 08:38 AM
i still run with the org cast manifold and catalysator så i have to weld it to the exhaust after the cat. about 10-15 min depending on if i hold the revs at 3000 rpm or just idle, longer time at idle

01-07-2013, 07:25 PM
Get a bag of ice and ice down the intercooler, try and repeat the problem with the intercooler chilled.

01-07-2013, 08:26 PM
The intecooler is not that hot after these 20-30 min, i can easly put my hand on it, i havent tryed to read the temp of it with a laser yet but will try the ice thing to the weekend. Any other things to try wile im at it you can think of?

01-07-2013, 08:40 PM
Well, heatsoak is the only thing that came to mind from the time frame. If you can stick your hand on the core, that's not it.

01-07-2013, 09:14 PM
i was thinking of it aswell but then my cat jumped up on the radiator ( hot ) and quickly jumped from it to the intercooler and sat there licking her paws. so i touched the intercooler and no problem. Hell i think my cats ass is more sensitive than my hand to heat so dont think it is that. the intake temp reader is in the AFM correct? just thinking if i missed som sensor that could be heatsoaked or something like that. When my friends knocksensor went crazy a couple of years his car made the same kind of problem. And i know that the ecu dumps a lot of extra fuel, changing alot of things just to keep the engine ok during this time. The car behaves like that but the only thing that i could think of is that the watertemp sensor is heatsoak do to som hotspot in the water bypas pipes under the manifold tricking the engine to belive that it is to hot, dumping extra fuel and when i run the car the water circulates thus cooling the sensor.

Will measure the sensor this weekend to se if it is out of spec

01-09-2013, 07:55 PM
problem solved

I changed cold start swith and water temp sensor. Changed the radiator cap to. I run a mr2 outlet with the cap quite close to the outlet. I changed the cap bacause i found that the expansion was overfull and i filled it up to full when i filled the engine with fluids. Unplugged the batterie for the night, pulled the ecu fuse ( didnt have to ) drived the car and tried to get the problem to return but nothing. It runs as is should.

So i think a combination of low water in outlet thanks to radiator cap not sucking water back into system, just pushing out when hot. The sensor could be broken och not perfekt. These two thing along with perhaps could start maid the ECU think there was to much heat in car and poured alot of extra fuel.

Cant confirm this but it is my theory

Want to thank you guys for helping me think epecially you MrWOT