4AGE Starting / Holding Idle problem

[thanhngo]

Hi,

Ok, I've tried my best to figure out my starting problems but my lack of experience with 4age's and sprinters is really making it hard. Coupled with the fact my car was purchased in bits and has never seen it running makes it all that hard. I need your experience and expertise!

I have a JDM Bigport, new fuel lines, new fuel filter, battery. Originally it would be really hard to start (almost impossible) but would startup straight away with "start ya bastard" and die straight away.

* I have resetted my timming back to 0 (has not been advanced to 10deg yet since its not running). I replaced the EFI main relay 1 and that solved the hard start problem. Now it starts up first or second time but dies straight away.

* Following that I replaced my EFI main relay and now it starts up, goes to 1500rpm and goes down slowly before dying (10-20sec). Any use of the gas pedal would result in instant stalling.

There could be multiple problems here but I wanted to see if I could get the car idling by itself at least first. Why would the car instantly die if gas is applied?

* I have calibrated my TPS and it seems to be in working order.
* Tried bypassing the ballast resistor (not even sure if there is one but I hooked up 12V to the positive side of the coil) with no luck.
* Tried jumping the FP and starting with same problems
* No diagnostics code (there was 7 which was TPS and gone now since I recalibrated).
* Hoses, wire connections are in tact.
* Earthing on Battery, Engine hook, Engine mount stabliser, and manifold/injectors are secure.
* electrically checked my COR and also tried a spare one with no luck.
* Tried replacing EFI relay 2 with a spare with no luck either

I guess my next step is to put in a fuel pressure guage to check fuel pressure?

I really need help me...

[Adash=P]

Have you checked the ignition side of things? What about the AFM?

[c2888]

Sounds like it is running out of fuel pressure.
See if you are getting voltage at the fuel pump whilst it is idling.
As when you go to START the ECU runs the fuel pump for 5 seconds, giving you enough fuel pressure to start it.

The engine speed picks up for a second before it dies?

Dan

[thanhngo]

Its got a MAP sensor. I got strong healthy sparks from ignition and it does start and hold revs for abit.

I can jump the FP wire and that causes the system to pressurise so FP is definitely powered and running (but not sure to what degree).

I do notice when I use the throttle at all, it stalls straight away. If I don't touch the throttle it would start, idle to 1500 and slowly drop until it stalls (over 20 seconds?). Starting the car with throttle would result in start and stall. So I suspect the throttle would give me a clue - TPS or wiring of it? It is calibrated and giving right resistances.

Here are the things I suspect.
* Fuel Pump (on its way out and not supplying proper pressure?)
* MAP sensor faulty (increase in vaccum/boost cause engine to cut but the engine does go to 1500 by itself and seem to run ok but doesn't hold revs?)
* Bad Electrical Gremlins

Anyone else had similar symptoms?

[rthy]

check the fuel filter if its pointing the right way

[78Rolla]

Deffinately check your fuel pump - that had me stumped once, the high pressure pump was on its way out. Another thing to check would be the injectors - make sure they havent seized.

[thanhngo]

Deffinately check your fuel pump - that had me stumped once, the high pressure pump was on its way out. Another thing to check would be the injectors - make sure they havent seized.

Brought a fuel pressure guage at Autobarn and hooked it up to my return line. The guage moves just a little bit on startup. I tried jumping the FP but again nothing. When I remove the return line there is some fuel but not very much.

So at least its a fuel system problem.

It will either be fuel link blockage or fuel pump but chances are higher with the fuel pump as the filter and lines are new.

Will report back.

[Hen]

A regulator on your return line will always read very low (unless you are plugging the return line with the gauge, in which case it should read very high). You really need to check fuel pressure between pump and fuel pressure regulator.

It could also be caused by a dodgy fuel pressure regulator (jammed shut or some other dodginess).

Hen

[thanhngo]

A regulator on your return line will always read very low (unless you are plugging the return line with the gauge, in which case it should read very high). You really need to check fuel pressure between pump and fuel pressure regulator.

It could also be caused by a dodgy fuel pressure regulator (jammed shut or some other dodginess).

Hen

Since its a JDM fuel line it has nasty banjos and I can't test using the guage unless I splice my fuel line which is kinda expensive to do. Anyway, I checked the line before the regulator and run the FP and it was shooting alot of fuel fast.

I did the same on the return line and it wasn't as pressurised but fluid was moving fast enough to fill 1L container in about 1 min I estimate. Sounds like how it should operate since the regulator and dampener should be making the flow steady. Thus I am getting fuel. Shouldn't my return line pressure guage read around 30-40psi as per FSM? Does this mean my FP is most likely dead or regulator?

So my car is probably starting on the cold start injector?

It seems like my fuel rail is getting enough fuel by my guesstimate. Going to service my injectors tommorow to have one less problem to think about.

[thanhngo]

I got my injectors serviced today- ITS ALIVE!!! couldn't believe it.

I was watching them being flow tested for the first time and they were all blocked up. 2 of them barely ran and 1 of them seemed dead. The other opened up after a few minutes but still very poor. Then it got ultrasonic cleaned in some industrial chems and flow tested again. They all ran with very good pattern.

Installed them and my car started up fine and it revved up doing the cold start duty! hooray. So it was the injectors! well partially because after that I got a whole lot of gasoline gushing out of my charcoal canister dump. So I suspect my return line and charcoal lines are reversed. Thats the reason why I got 0 pressure on fuel return line because the fuel was just flowing straight down the top as opposed to down the bottom. This explains why my charcoal canister is pouring out fuel as it shouldn't on a 10L's of fuel?

Anyway it doesn't idle without throttle but im sure its just timing (anyone got a timing gun I could borrow ) S.E burbs.

Does anyone know if its ok to run an open exhaust? e.g. it won't stall the engine. I just want to avoid towing my car down to the exhaust as I can do it on a temp registration.

Thanks for all your support!

[c2888]

That's awesome news.
What do you mean by open exhaust?
If you are gonna run the engine for any extended length of time you need at least the cast manifold section, or a set of extractors.
When you shut off a engine that doesn't have the exhaust manifold, cold air (much colder than the exhaust valves anyway) goes down the port and cools the exhaust valves much quicker than they would normally, and it can cause them to bend and distort.

Dan

[thanhngo]

That's awesome news.
What do you mean by open exhaust?
If you are gonna run the engine for any extended length of time you need at least the cast manifold section, or a set of extractors.
When you shut off a engine that doesn't have the exhaust manifold, cold air (much colder than the exhaust valves anyway) goes down the port and cools the exhaust valves much quicker than they would normally, and it can cause them to bend and distort.

Dan

Damn that sounds dangerous. Mine has a set of extractors but open because there is no cat joining the extractors to the catback system. It should idle fine with it open right?

I tried taping a spare pipe to join them together but it blew the tape apart (it was masking tape lol) but thats all I had lying around. Gonna get the all versitile "race tape" just to quieten it down but not sure if it will hold up to exhaust pressure / heat so probably just wasting time and money.

[DaveW]

but are you really going to be running it that much without the system on it? its not like ur driving the car this way.

ive started a car with just extractors on and it seemed ok, but it was only running for bout 30 seconds... i cant see any problem with running it over short periods of time with no system ie to set the timing? but thats not to say there isnt a problem... i just dont see one

[c2888]

Out of the end of the extractors is fine, just grab some earplugs

Dan

[DaveW]

hahah itll just sound like every dodgy VL you see driving around with a lack of exhaust