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Delco injection Esprit fuel pressure tester


tomcattom

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On 26/07/2022 at 14:44, tomcattom said:

the pintle is shaped slightly differently

Hi Tom,

There has been plenty of historic forum discussion around the two pintle shapes that are in common circulation. IMO, and as Barry says, judging by the picture, your new one is technically the wrong one.

Section EMH.3, Page 19 of the Lotus service notes says the pintle shape is important and any replacement should be checked for correct shape.

Previous forum discussion reports, that the one you have seems to work, but better idle control is attained with the right one.

I would send it back. Looks like PNM may have been sent a batch of the "other" ones.

As I said previously though, the fuel PCV became my prime suspect after you published your fuel pressure at idle.

IACV second on the grid, now looking like a non starter (pardon the pun)

Andy.

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  • Gold FFM

So I see @AndyPG. I've been reading through the thread Barry linked to. Probably should have read/checked that or other related threads first, but in my impatience to get the car sorted I went with one of the trusted suppliers without realising all the issues that can be had if you get the wrong IACV :(

I hopped on RockAuto a couple of nights ago and priority ordered a pair of IACVs to try. A pair I hear you say... well having read the various threads I saw note of the connector being oriented differently on teh 217-421 that seems to be the go to IACV. I did find it a bit trickier to get the plug back into the one that I've just fitted, so I went on the hunt to see if I could find something that was a closer fit to what was already on the car too. If I'm paying priority shipment I might as well get my money's worth out of it!

I ordered the 217-421 because that's whats in the thread, but while search cross references I also spotted the 217-428 which appears to have the same pintle design as 217-421, but the connector is clocked the same way as my original connector. But beyons that there really isn't very much technical information out there to compare all these different IACVs, which doesn't really help.

I've not changed anything yet, but here are some photos of what I received today. In all photos the IACV on the left is the 217-421, the middle is the original part removed from my car and on the right is 217-428.

1928869135_PXL_20220729_1049543742.thumb.jpg.413fa4730a980bcbcfb314f061e88699.jpg

377199115_PXL_20220729_105104645_MP2.thumb.jpg.f4e145af1995226ecb07d0490ca25a9e.jpg

PXL_20220729_105205336_MP.thumb.jpg.35d15c93f574b832784a73d1c2790959.jpg

I measured the resistance of the coils, and the 217-421 measures 50 Ohms, whereas the 217-428 and my original IACV coils measure a shade over 52 Ohms.

In terms of physical dimensions the pintles on these two new parts look closer to my original, but even under scrutiny with a pair of calipers all three are slightly different (not sure if that's by design or they're just bad pattern parts 🤷‍♂️). The one I was supplied earlier in the week is different entirely again.

Overall, the 217-428 seems to be the closest match to what was already fitted to the car, both physically and electronically, but I have no idea if what was on the car was original or replaced before, but what I do know it that prior to this cold starting issue the idle wasn't a problem despite the idle not being so good over the past few days, so I have no reason to suspect an incorrect part was already fitted.

I'll report back on how I get on with this new IACV, and if all else fails I have the 217-421 here ready to go to fall back on.

I'm going to replace the vacuum hoses today too and I'll check the fuel pressure again. Fortunately I do also have a spare FRP that I can fit too. Just don't want to change too many things at once because then I have no idea what was actually at fault.

Norfolk Mustard S4s #1 :)

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Well 217-428 has been fitted along with replacing the vacuum hose that connects from the non-return valve to the tee piece and then from the tee-piece to the pressure regulator and on first start there was no stall :happydance: although it did nearly die on me 😬. So not sure if that's a fluke or whether a drive later for the IACV to learn will sort that. I also chose to route the hose from the pressure valve the other side of the fuel rail to how it originally was on mine. The old hose was getting pinched between the fuel rail and the charge cooler and there were some noticeable gouges in the hose - perhaps the cause of my starting issues?!?

One point of note about the IACV that I hadn't realised; the two bolt hole wings on it aren't identical. One side is about 2mm wider than the other and as a result the IACV can only be bolted in one way round. What I didn't appreciate about the 217-428 is that it consequently means that the electrical connector now faces the back of the engine rather than forwards, but there is enough slack in the loom for the connector to still reach.

Norfolk Mustard S4s #1 :)

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1 hour ago, tomcattom said:

along with replacing the vacuum hose that connects from the non-return valve

Check the non return valve is ok. They can get gummed up solid.

(Obviously) You should be able to blow through it in one direction but not the other.

Andy.

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  • Gold FFM

I went out for a run yesterday and the car is still driving fine. Started from cold this morning again and while it didn't stall this time, the revs dropped almost to the point of stalling before it recovered. I've attached the logs I took from Espritmon, but I can't see anything immediately obvious that looks out of place other than the desired idle is at 2200rpm from the initial start which seems rather high 😕, but someone else might spot something I've missed.

I'm going to hook up the fuel pressure tester again tomorrow when I start from cold to see what it does now. I'll have a look at the non return valve and check that too.

esprit_7_30_10_41_51.log

Norfolk Mustard S4s #1 :)

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You need to do a full reset and then a full relearn.

the process is in the manual.

from memory 

car cold. Aircon on.

start car and let idle until fans come on and then go off - drive for about 20 miles

Only here once

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  • Gold FFM

Barry, that sounds like the V8 process from searching the forum based on your description.

While searching I did turn up this post which I've checked in my copy of the EMG manual:

I did reset the ECU through Espritmon and then went for a 20 minute steady run up the M40. I didn't try starting with partial throttle though. I'll try another reset tomorrow (battery off to be sure this time) and start it with partial throttle and see if that improves the learning.

  • Like 1

Norfolk Mustard S4s #1 :)

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6 hours ago, tomcattom said:

I went out for a run yesterday and the car is still driving fine. Started from cold this morning again and while it didn't stall this time, the revs dropped almost to the point of stalling before it recovered. I've attached the logs I took from Espritmon, but I can't see anything immediately obvious that looks out of place other than the desired idle is at 2200rpm from the initial start which seems rather high 😕, but someone else might spot something I've missed.

I'm going to hook up the fuel pressure tester again tomorrow when I start from cold to see what it does now. I'll have a look at the non return valve and check that too.

esprit_7_30_10_41_51.log 188.06 kB · 2 downloads


It might be more useful if that was in Excel!

Margate Exotics.

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  • Gold FFM

That's the format it comes from the Espritmon export. You can just treat it as a CSV if you want to load it into Excel @Chillidoggy.

I disconnected the battery and reconnected it yesterday and did a start as per the instructions in my last post with partial throttle gently released back to idle and it seemed happier. Then took it for a run at steady throttle openings to cover the various BLM cell ranges and upon my return from about a 20 mile drive it was idling beautifully. Came out to the car this morning, stall on first start once more and then the car was idling like crap again when I started it for the second time; its almost like the learnt data is being lost between runs 😕 The car is on trickle charger so I would hope its not a power issue.

Having done a bit of reading in the EMH that 2400rpm desired idle I saw on start is something to do with the Throttle Jack and EBPV speeding up the warm up; both items were removed some time ago. According to page 64a in EMH4 this desired idle will occur on engine start up at coolant temps between 17 and 31C; my start temp was 19C according to the Espritmon logs. Apparently a momentary stab of the throttle to >50% opening will switch this off, so I might try that next time I have the computer hooked up, but I'm pretty sure this isn't the cause of my poor starting and lumpy idle once it is going.

Norfolk Mustard S4s #1 :)

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From cold start its 40psi on priming (it does settle back a couple of psi after this, but its within the range the book indicates is permitted), then rises to 45psi on cranking and stays there on idle when it does start.

EMH stays 40.5-47psi priming pressure is expected, so I'm certainly on the low end of that scale, allowing for the accuracy of the gauge and my readings. It then says it should run a 30.5-55psi depending conditions, so I'm certainly running inside that range once started.

Apparently with the engine idling at normal operating temperature it should be below the prime pressure by 2.5-10psi (so 30.5-44.5psi by my maths based on prim pressure). I've not checked that, but given it runs fine when warmed up, I'm not sure there is any value in me checking that scenario.

Norfolk Mustard S4s #1 :)

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33 minutes ago, tomcattom said:

Apparently with the engine idling at normal operating temperature it should be below the prime pressure by 2.5-10psi (so 30.5-44.5psi by my maths

Hi Tom,

Not sure about your maths.

If the prime pressure is 40psi, warm idle should be 2.5psi to 10psi below that, the warm idle pressure therefore, should be 30psi to 37.5psi.

Can't see why you're calculating 30.5psi to 44.5psi as ok.

Have you tried that spare fuel PCV yet?

Andy.

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16 minutes ago, AndyPG said:

If the prime pressure is 40psi, warm idle should be 2.5psi to 10psi below that, the warm idle pressure therefore, should be 30psi to 37.5psi.

Can't see why you're calculating 30.5psi to 44.5psi as ok.

Book says acceptable pressure on priming is 40.5 to 47psi and the warm idle pressure is supposed to drop between 2.5 to 10 psi below the priming pressure.

So if you're on the low end of the priming range your expected idle range is:

  • 40.5 - 2.5 = 38psi
  • or 40.5 - 10 = 30psi

If your priming pressure is on the high end you would have:

  • 47 - 2.5 = 44.5psi
  • or 47 - 10 = 37psi

So by that maths depending upon you priming pressure and how much it falls by at warm idle, the widest expected range is anything between 30psi at lowest and 44.5psi at the highest. Unless I've misinterpretted what I've read.

Either way it feels slightly academic since warm idle isn't a problem, it's just the cold start stall that's the main problem here.

16 minutes ago, AndyPG said:

Have you tried that spare fuel PCV yet?

Not yet Andy. I didn't want to change more than one thing at a time otherwise I'll never know what fixes it, if I ever solve this. It's the next thing on the list to try, but it will have to wait until tomorrow.

Norfolk Mustard S4s #1 :)

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1 minute ago, tomcattom said:

Unless I've misinterpretted what I've read.

Hi Tom,

You have misinterpreted it.

The calc needs to be done from your initial prime reading , not the possible suggested range of prime readings.

Your fuel pressure should be between 30psi and 37.5psi at idle.

The inlet manifold vacuum pulls the pressure down from the initial charge pressure.

Please change the fuel PCV.

It's almost certainly faulty.

Andy.

 

 

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  • Gold FFM

I was making a general statement based on what I read in the EMH that for Esprits as a whole the idle pressure could be anywhere between 30 and 45psi depending upon what the priming pressure is and how much it falls back by. Sorry if that wasn't clear. For my car based on the low end priming pressure you are right that I'm expecting 30-38psi when warm. 

Norfolk Mustard S4s #1 :)

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11 minutes ago, tomcattom said:

For my car based on the low end priming pressure you are right that I'm expecting 30-38psi when warm. 

Absolutely.

There's a huge possibility that this is your issue.

I am assuming that the fuel PCV vacuum pipework is all per spec.

If you are 100% that the vacuum pipework is good, change that fuel PCV.

If you are not 100% that the vacuum pipework is good, read on.

Pull the pipe off the fuel PCV and off the non return valve.

Put your thumb over the end of the pipe that went to the non return valve and blow down the fuel PCV end. This will prove that the plastic T Piece isn't blocked. You should be able to blow through into the inlet manifold via the t piece.

Now put a screw in the pipe that was connected to the non return valve and reconnect the fuel PCV. Start the car. This will eliminate the pipework from the non return valve to the crankcase breather. If the fuel pressure issue is still there, the fuel PCV is faulty. 

Andy.

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Managed to convert your file to Excel.

First thing I noticed is your desired idle is 950. I believe 987 is the correct desired idle for the S4s. I'm not yet convinced it's the FPR but happy to be proved wrong! Have you by any chance got a spare ECU?

Margate Exotics.

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48 minutes ago, Chillidoggy said:

I'm not yet convinced it's the FPR

Hi Ian,

Convinced?... Me neither.

As with everything Esprit related, there's always lots of wild goose chases.

I just think it needs eliminating next. It's a contender.

Andy.

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  • Gold FFM

Just been out and whipped off the chargecooler again to gain access to the FPR vacuum pipework and removed the non-return valve to check it, since that is one thing I hadn't done when renewing the vacuum hoses in that area. It seemed to retrict flow in one direction and not the other, but didn't seem great, so I removed the NRV from the front of the engine for comparison and it put up significantly more resistance in the reverse direction; looks like the one from the rear is gummed up as you suspected @AndyPG. I tried flushing it with carb cleaner to no avail so I now have a new NRV on order, hopefully be here in the next few days.

I've left the FPR unchanged for now. Will address that if the NRV doesn't improve matters.

Norfolk Mustard S4s #1 :)

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7 hours ago, Chillidoggy said:

Managed to convert your file to Excel.

First thing I noticed is your desired idle is 950. I believe 987 is the correct desired idle for the S4s. I'm not yet convinced it's the FPR but happy to be proved wrong! Have you by any chance got a spare ECU?

That's interesting Ian, because according to Espritmon, when I replay the log file the desired idle never goes below 1050rpm.

As for a spare ECM, the only spare I have is my original which has a faulty QDM on the fan control circuit, although for a cold start test I guess I could try it if I got desperate.

Norfolk Mustard S4s #1 :)

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2 hours ago, tomcattom said:

That's interesting Ian, because according to Espritmon, when I replay the log file the desired idle never goes below 1050rpm.

As for a spare ECM, the only spare I have is my original which has a faulty QDM on the fan control circuit, although for a cold start test I guess I could try it if I got desperate.


I just thought that if you’ve got a usable ECU, then it’s free, and you may not need to remove the original from its bracket for a cold start test.

Margate Exotics.

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3 hours ago, tomcattom said:

Will address that if the NRV doesn't improve matters.

Hi Tom,

I don't think new NRV's will improve your issue.

The one at the rear prevents the charcoal canister seeing boost and the one at the front stops the crankcase vent seeing boost. During starting and at idle there is no boost. Obviously it is good for the NRV's to be functional for their respective systems to work properly.

I'd press on with the FPCV.

I have a working spare if you need to borrow one.

Andy.

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  • Gold FFM

Non-return valve was replaced last week and didn't make a jot of difference to the stalling issue, but it had failed so not a wasted effort to replace it.

Attacked the fuel pressure regulator this afternoon and after a bit of a game getting the fuel return host installed in the new item due to ill-fitting parts supplied with the regulator, it's now in and upon first start it didn't stall :happydance:, but it definitely sounds like it tried to.

I videoed the fuel pressure readings from my gauge on first start up. I primed twice because the pressure on the first key turn seemed low, probably due to me draining the fuel to fit the new regulator and priming only being for a fixed duration. At around the 30 second mark in the video you can hear the slight stumble a few seconds after starting; previously that stumble would result in a complete stall. The jury is still out on whether this has cured it yet.

I'll try it again later/tomorrow once its cold again to see if that was just a fluke start or the pressure regulator has genuinely cured the starting issue.

Norfolk Mustard S4s #1 :)

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Hi Tom,

Looks promising but I would still expect to see the fuel pressure drop by about 5psi on start-up.

Are you sure the FPCV is seeing vacuum from the inlet manifold?

Did you try blowing down the hose and through the plastic T piece into the inlet manifold?

Andy.

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