Welloilbeefhooked

iTrader: (3)

Hi all,

I have a new semi forged ej207 with sti3 heads, 550cc denso inj's and a td05 big 16g turbo fitted in my car and it drives fine.

However, it starts from cold first time every time without issue. While it runs up to temp on idle it's as sweet as a nut but when it gets to it's idle of 850rpm it starts to hunt. Not violently, it's more a surge up and down of around 100rpm.

It's running 14.7 at idle and turning the lamba off in esl doesn't change a thing, it runs the same. The fuel trims in esl are pretty much bang (101) on and the inj scale is at 0.83. Running a MAF with standard airbox and cosworth panel filter. NGK 7's for the plugs

Driving and coming on and off throttle is smooth and there is no sign of any poor running. It does however seem to have a hot start issue, which it did on the last engine and still does now. Only by flooring the pedal on starting will it start. Doesn't have to be majorly warm either. No smell of fuel at all.

As part of the build I've replaced the following items.

Standard turbo inlet pipe is new
Cam and Crank sensors
Oil Pressure Sensor
ECU Coolant Temp Sensor (reads fine in esl)

To try and rule out other components I've swapped the following

ISCV x 2
Throttle Body x3
TPS x3
Coil Pack x 2
MAF x 2 (cleaned)


I've spray carb cleaner around every gasket and don't appear to have any leaks. I've checked all vac lines and found no issues. All earths are good too.

I think I'm left with the injectors, spark plugs, wiring and ecu. Everything ran fine before on the other engine, which used the same ecu, wiring but not plugs or injectors.

Any ideas or things I've missed?

1509joe

iTrader: (2)

Have you checked the turbo to inlet pipe rubber or possibly a sticky PCV valve.

Welloilbeefhooked

iTrader: (3)

The rubber on the turbo hose was good when I fitted it but who is to say I haven't damaged it when I fitted it.

I'm so hoping it is a sticky pcv valve but I seem
to remember it being free when the manifold was off.

I'll check later and post back.

Welloilbeefhooked

iTrader: (3)

Duplicate

Welloilbeefhooked

iTrader: (3)

Right, PCV valve is moving freely and you can feel the spring closing the valve. The turbo hose all looks good.

I did find that the small breather pipe that goes from the turbo hose to the crankcase breather block (the one with 2 pipes coming off it) wasn't on fully. Possibly that but I won't know until tomorrow when I get time.

Would that pipe be enough for the symptoms I have?

1509joe

iTrader: (2)

Possibly but every little bit helps.
Plus they can crack.

Welloilbeefhooked

iTrader: (3)

Large pipe from engine block to plastic 2 way block is cracked. Just ordered a new one.

1509joe

iTrader: (2)

Hopefully that will cure it.

Welloilbeefhooked

iTrader: (3)

1509joe

iTrader: (2)

Its not that bad but definitely wouldn't help was the clip right over it?

Welloilbeefhooked

iTrader: (3)

Hose above has been replaced and there is no change. I'm thinking of pulling the injectors to check seals in the coming week but tonight I've noticed that the car idles smoother when the lights are on. Switch them off and it idles less smooth.

I'm wondering what electrical items would cause this. The battery is new so would the alternator cause these symptoms?

I've checked the earths and ran an additional earth from the battery to the inlet manifold and the same with the ecu.

​​​​​​ive also bypassed the purge valve just incase there is a problem there.

1509joe

iTrader: (2)

Have you checked BOV/spring in it.

Welloilbeefhooked

iTrader: (3)

The dv is an stock one so I'm assuming it can't be adjusted?

1509joe

iTrader: (2)

Can still be broken

davoid

IACV?

RetroGenGamer

iTrader: (1)

as above has mentioned id check the iacv,
and does your ecu have an idle learn feature? had similar in the past with apexi pfc and had to reset it and do the idle learn again,
on pfc you start running them for 10 mins on idle , then add electrics for the next 10 mins , then aircon for the next 10 so it can make the compensations for when theirs electrical loads in use (turn heaters/lights/ rear demister etc on)

1509joe

iTrader: (2)

No ESL hasn't that function and as said in his first post he's tried two.

bludgod

iTrader: (3)

ESL maybe doesn't have that function defined and visible to you, but the routine in the background is certainly there to make small corrections for a nice idle. Although you've tried lambda feedback on/off have you tried briefly switching to speed density ignoring the MAF input? If its better with the MAF off it could be the MAF sensor or still another vac leak somewhere. Wouldn't take much to throw off the idle as there's only a small amount of air coming into the engine to begin with so anything extra can give you a lumpy/rolling idle. Also if its better with the electrics on what if you bump the target idle in ESL does that improve things any?

1509joe

iTrader: (2)

Good point Sir it sort of slipped my mind it was attached to the standard ecu

Welloilbeefhooked

iTrader: (3)

I'll try raising the idle to see what happens. I've also bought a standard lambda sensor to try that although I'm not convinced that's the issue.

Next move is inlet manifold off again to check all pipes and gaskets.

Welloilbeefhooked

iTrader: (3)

Out of curiosity, how would a broken dv affect the idle? Leaking past and into the vac line on the manifold?

I tried clamping that hose off and it's made no difference so I'm assuming the dv is ok?

1509joe

iTrader: (2)

If the DV spring was weak or broken it would recirculate air round the system albeit metered air but it's not going where its supposed to go its bypassing the engine as such.

jaygsi

iTrader: (46)

When i take mine for mot the guy holds it at 3,000 revs for 5-10 mins and it starts hunting. Never happens any other time and freaks me out.

Welloilbeefhooked

iTrader: (3)

The dv is fine. Had it off the car today and checked the spring which moves as it should. I've checked everything for leaks and can't find anything.

In the esl software is appears to show the coolant temp correctly, so do I try another cts?

Is it possible I've got a split bottom injector seal or an injector that's constantly leaking slightly? The first is easy enough to check and both would explain the hot start issue. Checking for an injector leak poses a problem and they were checked, cleaned and flow tested before I fitted them. Would Mark at Lateral leak test them during his tests?

I am thinking possible ecu issue but it ran fine with the old engine and old injectors. It did however have the same hot start issue, although idle was fine.

So to recap, it starts immediately when cold and runs smooth right upto when it drops to 850rpm when warm where it starts to idle irraticaly. Once warm and switched off it will start again immediately, but if left for 10 mins it needs to crank a while before starting.

​​​​​I think I'll swap back to the original injectors this week.

​​​

Croney

I had a hot start issue, not sure what finaly sorted it as i dud lots but after I found a split hose at the rear carbon filter and fixed that, cart say I noticed it again, think its part of the IVAC
as mentioned above

Welloilbeefhooked

iTrader: (3)

I now have a perfectly idling and hot starting car!!

It was the injectors. Not sure if they are fauly yet or if it was definitely the seals. The 550cc denso injectors had both a top and bottom aluminium adapter with both internal and external seals. Parts of the ali where the seals sit show some light corrosion and 2 of the seals look slightly cut or nipped, probably happened when fitting.

I've now fitted a set of 440cc phase 1.5 injectors with new seals and not only does it idle smoothly, the afr's are more stable on the WB.

I left the car hot and returned 20 mins later and it started within a second, just.as it does when cold.

Next task is an oil change as it's probably contaminated with fuel.

Thanks to everyone for the help and suggestions!

1509joe

iTrader: (2)

stockcar

the guy you were going to ask about seals cold test / clean / refurb your 550's no issue.........

Welloilbeefhooked

iTrader: (3)

I'll post them Monday 👍