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The mkiv Supra Owners Club

Warm start problem - ongoing investigation


Ian C

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When the car does fire up after said cranking time does it run properly or abit lumpy and is there any smoke from the exhaust, the only reason i ask is that i had your exact problem a couple of years ago and it turned out to be weeping injectors when standing.

I checked the plugs and cylinders like you have and they all seemed dry but ryan was so insistant on the problem being injectors i pulled them and set them up on a bench, i poured a small amount of petrol into each injector and low and behold 3 out of 6 dripped straight through,i`m pretty sure the problem was having no fuel pressure on shutdown then the ball or pintle doesn`t seal against the seat?, having the injectors cleaned and tested could sort them out. i just replaced mine as they were 2nd hand anyway, hope this helps.

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You could quite easily test your theory without changing the gasket. Install a switch in the cabin that replicates the "paper clip" method of forcing the fuel pump to operate (bridging the FP and B+ terminals in the diagnostics port connector).

 

I suggested that a few posts back, but he really wants one of those gaskets :)

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After going down the electronics route and finding nothing untoward, I'm still thinking it's heat soak to a (£2500) change of ECU is going to work around the issue using some tweak rather than actually fix the vapourisation in my opinion. A twenty quid thermal gasket sounds like a better first step to me :)

 

That was my intention with the Syvecs comment. :D

The Stock Fuel System retains Fuel Pressure for a long time staying at 3 bar. When i changed to a Walbro 255 and Aeromotive FPR the pressure went away fairly quick(under a minute) which i think was the main reason for the starting problem after a few minutes. I remember that when i did the 12V Pump mod and let the Pump work for 5-10seconds before starting the engine that it started way better. So worth a try before pulling everything apart :)

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I'll certainly give some thought to a manual pump prime as a test, to refresh the fuel in the rail before attempting key-on :) Testing opportunities are nonexistent at the moment, nightshifts plus other stuff going on.

 

Bignum - once the car fires up, it's fine. Idles okay, no lumpiness. Also, I've got a fuel pressure gauge on the FPR and while it does drain away, it's not too quick to do so, I've still got a good few PSI in there. Having said that, this is all "I'm sure I remember seeing this" rather than "I've tested that scenario and written it down", which is what this problem is turning out to need, so I'll revist that as well.

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  • 2 weeks later...

So, an update. I had a nice drive to Halfords to get service items for the other cars and on the way back the idle starts getting a bit lumpy. I got past someone slow at a two-to-one traffic light filter and on lifting off from high revs in 1st gear I got a big "blat" noise from the exhaust. Overrun was more burbly, revving caused bangs and pops. Hmm. So I got home and checked the narrowband O2, that was working fine, but the wideband wasn't twitching around like normal, it was quite static. Then it started running on 5 cylinders at idle. Seeing as that thermal gasket is in the post I thought I may as well strip the intake side and check out the injectors anyway.

 

I found this on cylinder #3:

attachment.php?attachmentid=173253&stc=1&d=1375626987

attachment.php?attachmentid=173254&stc=1&d=1375626987

 

The plastic tip of the injector is badly cracked. Also, the valves happened to be fully shut on cylinder #3 after I moved the car in the garage before starting work, and there was a big pool of fuel in the intake channel. So it looks like a leaky injector after all.

 

I'll send them off to Chris Wilson for flow testing etc, not sure what I can do with this cracked one though but I'd still be interested if it does properly leak or not.

 

 

Also I dropped the fecking throttle body and cracked open the TPS, so I might be in the market for a replacement if it doesn't behave properly after aralditing it back together.

 

-Ian

Broken injector1.jpg

Broken injector2.jpg

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That could very well be it mate , if it had been getting worse but if it was from day dot it may not be, could be very similar to mine , as I had a couple of leaky injectors fitted new injectors and thermal gasket and now starts every time but , I can still tell it doesnt like it when left for a little while but still starts but dont show me up lol. Hope you get replacements easy as I know injectors can be a pain I had to modify mine even though they was the exact same part number.

 

You can get a flow test done but you may just aswell save the £100 as you know you need a new set anyway, it is not advised to mix old with new injectors

Edited by mellonman (see edit history)
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I'll be dropping Chris Wilson a line to discuss the matter. It deffo wasn't there from day one as CW cleaned and tested them for me prior to installation :) I wouldn't have installed one with a crack either. Hopefully sorting the injectors and the thermal gasket will clear it all up.

 

I don't really want to change the injectors as it'd end up being a remap job no doubt and the idea of having to do that bores me these days :(

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I'll be dropping Chris Wilson a line to discuss the matter. It deffo wasn't there from day one as CW cleaned and tested them for me prior to installation :) I wouldn't have installed one with a crack either. Hopefully sorting the injectors and the thermal gasket will clear it all up.

 

I don't really want to change the injectors as it'd end up being a remap job no doubt and the idea of having to do that bores me these days :(

 

No not the injector problem the starting when hot problem, if it was there from when the injectors was first fitted it could well be the same once replaced,

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No not the injector problem the starting when hot problem, if it was there from when the injectors was first fitted it could well be the same once replaced,

 

Ah yes, this is true, but I think I used to mask it by running a turbo timer. I reckon the thermal gasket should sort that out, and that it's the ally posts on the HKS rail that's sinking heat into the fuel. I'll repeat my temperature measurements after fitting it all.

 

My injectors look to be long out of production though :( I've written to RC Engineering to see if they have any spares, if not I'll be looking at new injectors and a map tweak, sigh.

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Ah yes, this is true, but I think I used to mask it by running a turbo timer. I reckon the thermal gasket should sort that out, and that it's the ally posts on the HKS rail that's sinking heat into the fuel. I'll repeat my temperature measurements after fitting it all.

 

My injectors look to be long out of production though :( I've written to RC Engineering to see if they have any spares, if not I'll be looking at new injectors and a map tweak, sigh.

 

Remap with just injector change is not that bad, probably just have a scale setting to change and maybe responce time, must admit my car has yet to fail to start since my injector change and thermal gasket so hope you have the same luck mate,

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Good news, RC Engineering got straight back to me and told me they were Nippon Denso's that they modified for a customer to 720cc. They'll clean, test, and balance, and replace all the pintle caps and o-rings for $24 an injector. That should sort out the leakyness as well. I just have to ship them to the states and back :D Much cheaper than buying 6 new ones and having to remap :)

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  • 2 weeks later...

I got my injectors back from RC Engineering, along with a nice report:

 

attachment.php?attachmentid=173908&stc=1&d=1376930868

 

The "before" table makes scary reading :eek:

 

I'm hoping I'll notice a difference when I refit them this week :D

 

RC Engineering were great, excellent customer service. They responded within a day to emails, despite the time zone difference, helped me out with my questions, and delivered what they said they would. It was $24 per injector to sort out, which was good value.

 

What wasn't good value was UPS, whom they used to send it back. Cost me $100, almost as much as the work on the injectors! And when it shows up, they ask me for £41 owing :blink: I checked the invoice, and customs have charged me VAT on my own 10-year-old flippin' injectors! Then billed me £11 on top as a penalty because I hadn't paid the VAT up front! :complain: Needless to say, there is an angry phone call looming on the horizon, paying VAT on my own property is a bit rude.

Injector flow test.jpg

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:complain: Needless to say, there is an angry phone call looming on the horizon, paying VAT on my own property is a bit rude.

 

Best of luck with that one, I don't call them Robin Tax Hoods without good reason.

 

The clauses make it quite clear, that if you don't pay up they'll keep your property and if you do, under no circumstances will they give it back. :shrug:

Edited by David P (see edit history)
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  • 3 weeks later...

Right, it's all put back together and has been used a couple of times. While I have done a bit of a troubleshooting no-no by making multiple changes at once, here's the situation now with refurbed injectors and the thermal gasket in place:

 

1) The fuel rail now stays cool enough to touch even after 5 minutes of engine bay heat soak :D

2) The start and idle is much better and it doesn't throw a big cloud of grey out the back on cold start like it used to

 

It still had some trouble hot starting so I did:

3) added airflow (and therefore fuel) in the 0-5% throttle, 500 to 2000rpm range. I noticed it runs quite lean around that area and perhaps that wasn't helping a warm start situation.

 

Went to fill up with fuel today, my benchmark test, nice warm day, nice warm car, started first go. Wasn't the smoothest start ever but looks promising :thumbs:

 

Edit to say, cleaning the injectors was a result, not only does it remove the potential danger, but the car feels smoother and 'happier'. Acceleration through the rev range feels good. This may be placebo effect, but I like it :)

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Nice to see its better, the only problem that I have found by adding the fuel in at the crank speed it that when you start from cold you get abit of black smoke, but is definitely worth the trade off with my set up

 

Also the better acceleration feeling maybe down to the stock fuel trims being reset

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  • 9 months later...

I'll just resurrect this with some good news :) After the injector refurb, the thermal barrier gasket on the lower intake runners, and fixing the cambelt tensioner, it still arsed around at warm start, much to my frustration. I went back to basics and had a think about hot starting conditions. It's going to be failing to start because either it's not getting enough fuel to kick off, or it's getting too much.

 

I recall from mapping B'Haves' soop that it had this strange behaviour and I figured out a trick with the airflow map on the E-manage to fix it. I'd sort of tried in the past to apply it to mine but it didn't work so I discounted it, but I'd not really tried hard enough. My map now has a load site for 500rpm and 600rpm. Anything below 500rpm is cranking speed, anything above 600rpm is normal idling and running. That gave me a specific cranking load site to ferkle with to try and make it work. I had the car warm, tried to start it, and it did its "I'm now just going to turn over and not even try" thing. So I reduced the amount of airflow I was pulling out (from about -30% to 0, a big change in values to provoke a big change in behaviour) and the thing turned over twice and burst into life :D It's never ever done that until the engine has cooled down, once it's got a strop on.

 

Long story short, after some tweaking of that load site and the water temp trim map, I've got a car that starts when hot and cold and warm :yahoo: I'll still do some tweaking around it but that's all it is now, the main problem has been solved. I think I never got the problem when I first mapped it due to my driving habits - the petrol station was much closer so it never got warm enough to fail to start after filling up, and all my other journeys didn't end in a 5 minutes stop before I tried to start it again. The problem was always there, the 'change' that caused it to start going wrong was me moving house!

 

I don't think anyone I ever mapped an E-Manage for had this problem as 650cc was about the biggest injectors people went up to, and I suppose the problem doesn't quite manifest due to the smaller airflow adjustments needed. If anyone I did is having this problem though, I'll happily tweak their map for them the same way I've done mine.

 

-Ian

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The other bonus is that I've finally got new tyres on, Pirelli P-zero's. Not Rosso or Corsa or anything, just the straight up P-Zero's. They look nice and fat compared to the Rosso's and the joy of having tyres that aren't 7 years old means it absolutely doesn't tramline any more, not a bit :D That combined with CW suspension (and the fact it starts) means it's an utter joy to drive now :love:

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thats what i have to do with mine is add more fuel in cranking but as i only have tha fic i cant add it to just the water temp may so its stays with me all the way to cold start and my did chuck out some black smoke on start but i have now put it back to closer to stock to try and stop it happening i just have to live with a medium between both ,

glad you sorted yours though

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  • 1 month later...

Ian: can you let us know a bit more info on "creating a load site for 500rpm and 600rpm"? I have exactly the same issue on a 1JZ running an EMU with 550 USDM injectors.

 

Update: got the load sites sorted. But what about the the temp sensor map? Do I need to buy another harness+sensor for it?

 

Cheers.

Edited by zedhex (see edit history)
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