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Lumpy, Hunty and Puffy.


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Some of you will remember the saga last year when I originally installed the 3.9 with flapper into my 110 that I had some 'issues' with its erratic running. Now I have been using it (not a lot) for a year, I can be a bit more precise with the issues and hope that I can find a fix with some more bright ideas.

So...

1) Start from cold. Fires up in good time, but runs lumpy with black smoke from the exhaust. After around 30 seconds (this depends on outside temperature - longer when v. cold), the lumpyness and smoke disappears and idle speed rises quite considerably.

2) Driving. Most of the time drives fine, but sometimes I do notice that it is missing some umph. The umph can suddenly reappear instantaneously (like a switch has been flicked) and it runs completely on song.

3) Hunting. When slowing down or sitting at junctions/lights, it can hunt quite (very) violently. Raising the revs a bit does temporarily solve the problem, but can be cleared by a good blast when it will subsequently idle fine.

The only reliable fault is number 1, the others are intermittant.

The CO reading at the MOT was well within the limits (very low actually - probably because I had the ECU adjusted well down because of the above).

As per last year, all ignition components have been changed. AFM changed, temp sensor changed, ECU changed to fancy adjustableone and timing set at both TDC (as per manual) and advanced up to about 8 degrees (following another post on here with a hunting RR). Am about to source some injector cleaner - any suggestions?

Are the temp sensors different (as in different ranges) for flapper and hotwire? Could the injectors just be shagged? Also, if anyone has a good (and I mean good :) ) air bypass valve, or a source for a good one, could they let me know.

I have it booked in to connect the LPG, but would prefer to have it running better on Petrol first, although I guess once the LPG is connected, I will be able to tell if it is fuel or ignition related.

Over to you guys.

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Coolant Temp sensor (CTS) Front of inlet Pass side, often fails or can be faulty on and off :(

This when its faulty / fails makes the engine think its cold / colder than it really is, and hence it richens up fuelling, this when noit wanted will give black smoke as a clue from the exhaust, ffs do fit a genuine one, there about £14

Throttle Pot could be faulty / sticking - see diagnostic guide but basically with a multimeter a- check the setting as .325 and b - check it has full smooth linear range as the pedal is press down (engine off)

I will have a think, but do consider going therough the test manual of fault finds that I placed in the Tech Achive.....

Hunting at tickover is 99% often air leak, get some WD40 and spray carefully :huh: it is inflamable, esp around inlet manifold to heads, and check all air pipes for snug fit no splits etc. Lastly fuel filter can give driving probs if not allowing fuel back, I have also fitted the "Fridge" mod of a chep plastic fuel filter in the return (low pressure) to tank, as a visual aid to both retun fuel and cleanyness

Nige

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All these symptoms point to a failing ECU,I know you have changed it but I would try another from a known good car - its really the only way.Or put your ecu on another car and see how it goes.So many of those early ecu's die slowly in old age with the surging and hunting idle,I even used to keep a known good one on the shelf.Next to it on the shelf are probably 5 or 6 with "dead " or "poor idle" written on them.

Now 3.9's are being scrapped at such a rate it may be worth thinking about changing to hotwire.

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Thanks guys.

Nige - CTS was changed last year for a Bosch one. Have been through all tests on sheet with multimeter and throttle pot. set OK. Slight drop in reading for injectors as they go through the LPG ECU, but the rest are OK. Air leak is a possibility, especially as issues seem to reduce when engine nice and hot, but would this cause the initial rich running (and going back to last year, potentially a lazy air bypass - but where to find one of these?)

Ally V8 - I have been trying for a year to find a known good ECU, as I agree, it would be good to rule this out. I too have a selection of 'known' good ones from cars driven by an elderly relative that have more silt in them than the Amazon delta. So, if you know of one, let me know. I think if I changed, I would go Megasquirt (FF HobNob fund alert!).

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If you are sure that there are no inlet air leaks and the CTS is OK then..........

Are the faults you describe like this…………

http://www.carelect.demon.co.uk/rrp1.html

The 14CU ECU is renowned for failure of the injector driver transistors. The RCA pair can be replaced with a pair of BDX65B’s but even these are hard to come by now. The problem here is that the RCA18483 devices develop emitter to collector and base to collector leakage………..

Open up the ECU and look very carefully at the output pair. These are easily identified as TO3 devices bolted to the PCB. If they have already been changed then it could also be a dry joint due to the continual heating and cooling process whilst in service. Carefully reflow the solder around the base & emitter pins of the devices.

Here is the diagram of the output.

gallery_269_524_127762.jpg

I think I have a known good 14CU under the bench.

:)

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Probably won't help but here goes. 3.9 hotwire with similar symptoms.

I had lumpy running, intermittent low power etc. as you describe. on petrol and LPG

everything checked out fine, CTS, TPS, compressions etc. all ignition components are newish LR OE.

The fault turned out to be an intermittent (slightly corroded) plug on the throttle pot lead.

Checked out resistance and voltage-wise ok when not running but showed up on my laptop connected to the lpg ecu.

(LPG is a single point Leonardo closed loop with lambda)

it would suddenly lose the tps signal and almost stall then start to hunt.

I reckon the vibration from the engine was shaking the plug/socket just enough to break the contact and upset the ECU.

cleaned up the plug/socket and slightly squashed the female receptacles on the plug to give a tighter connection.

Seems to have done the trick up to now.

Bob

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The cold start running rich problem points towards the air bypass valve. Worther pulling off the inlet feed to it to see whether it is opening on a cold engine - you should be able to visually see this. You might even be able to manually force it open to see what effect this has.

These type were used on Jaguar six cylender fuel injected engines from 1979-1986 so should be plenty out there second hand.

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I had all of the problems listed above a couple of weeks b4 fitting megasquirt i fitted a wideband lambda sensor and ran the log while i drove it.

turned out it was running very lean all over the shop. infact the only time the Air fuel ratio dropped into rich was (below 14.7:1) when i planted my foot down hard then it returned to lean.

The engine seemed to hesitate alot, often back fire and slam the Flapper shut. it hunted all the time and no matter what i changed i couldnt get the damn thing to run right. I had been through the diagnostic manual a few times, checked everything twice and couldnt fault it.

Although in the end it blew back and ripped the pipe between plenum and AFM and maybe damaged the AFM in the process. I replaced this with the only pipe big enough that i could find which was too long. making the AFM too far away from the plenum and causing more trouble.

So what did i do. well after observing Fridge and HFHs posts across the forum and looking on the internet for almost 6 months i fitted megasquirt. wiring it directly into the old ECUs wiring plug harness (not cut and shut) actuall pin plug in connectors.

took off the AFM and wired a air temp sensor into the AFMs connector. popped the purple wire connector from the diode pack (the red one) base and connected this to term 86 of the fuel pump relay and connected were this used to be across to another pin on the diode pack (following the wiring diagram on extraefi.co.uk)

Basically i didnt want to butcher the origional connectors incase it didnt work.

Checked a few things in megatune. looked ok after a day playing with soldering iron and wires so strook it up and it ran like a bag of spanners i mean it was a rough base map.

Went to the pub,

came back the next day after a good read of the mega manual set engine constants for 8 cylinders and 8 injectors etc and it no longer hunts. accellerates like something not right. doesnt hesitate at all.

infact theres alot more power just from this base map i was provided with

Although its running rich all over the shop now that can be tuned. maybe something to do with me not knowing the correct injector flow rate for a lucas flapper type system on a 3.5 Rv8

basically it went in running rough as hell hunting etc. i plugged megasquirt in and set a few things and now it runs better. Point to note is if you need parts for it your looking at about £400 for a recon AFM and ECU.

I would sell you my ECU and AFM but i know it wont solve your problems because the full efi system sucks. big time.

Nige HFH is helping me with my megasquirt map (cheers Nige)

Not saying your sensors aint faulty. but the lucas system plagues even the most experienced with its randomness

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Right I've had enough. Will try one more ECU and then out with the petrol and matches to the Flapper :angry:.

So.... Megasquirt.

Am planning the system at the moment (you can tell I have a great deal of faith in the Lucas ECU's). Am I correct in assuming from my research that even though the rover injectors are currently wired independently, that they fire as a bank? If so would this banked squirting be OK for my injection LPG as well. Reason for asking is that I can then run a single feed for each bank from the MS ECU split into eight (4 petrol, 4 LPG) on each side in the engine bay, reducing wiring considerably. Presumably if running dual maps (Petrol, LPG), these feed out of the same pins (left and right bank) on the ECU.

Is the P38 manifold any better than the hotwire (I want to change to a system with readily available injectors). For a tidy install, I see that the P38 has coil packs already mounted, so could I use these directly driven from MS (with appropriate direct drive chips)? - Or can I bet that there are a rash of reliability issues associated with P38 coil packs? - made by the Prince by any chance?

Just at the stage of collating the best setup at the moment. Although my flapper manifold is currently drilled for LPG, I do have concerns that the injectors are not readily available when they pack up, so as I am going into this, best to start at the ideal and then tweak to the practical.

And I was meant to be selling this vehicle as I don't have enough hours in the day.... hey ho! :rolleyes:

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Am I correct in assuming from my research that even though the rover injectors are currently wired independently, that they fire as a bank?

Yes.

If so would this banked squirting be OK for my injection LPG as well.

Can't see why not.

Reason for asking is that I can then run a single feed for each bank from the MS ECU split into eight (4 petrol, 4 LPG) on each side in the engine bay, reducing wiring considerably. Presumably if running dual maps (Petrol, LPG), these feed out of the same pins (left and right bank) on the ECU.

Depends what you're meaning here - MS has two injector outputs, A and B. In normal mode it fires A+B simultaneously, or in alternating mode it fires A, then B, then A, then B... In Staged mode, it runs on A until a certain point then either phases in A+B or switches to B (for example if B was connected to NOS). I believe you can also have table switching set up so that it runs injector output A from Table 1, then when you switch it changes to table 2 with output B.

It also depends how your LPG kit is setup, and how you ultimately want the whole thing to work.

Is the P38 manifold any better than the hotwire (I want to change to a system with readily available injectors).

The later Thor manifold is slightly better but probably not worth the hassle, the 3.9 injectors are readily available and quite frankly how often do they go wrong?

For a tidy install, I see that the P38 has coil packs already mounted, so could I use these directly driven from MS (with appropriate direct drive chips)?

Rog has done this, the only faulty part of the installation was the P38 coil packs. Switched to Ford ones and it was much better. :lol: Also, driving coils directly from the MS is a lot more faffing about than using an EDIS8. Incidentally, EDIS8 would happily drive those coil packs, a coil pack is a coil pack the same as a normal car coil is a normal car coil, there are a few differences in size, shape, etc. but most of the major ones are similar enough.

Or can I bet that there are a rash of reliability issues associated with P38 coil packs? - made by the Prince by any chance?

Yup, and frickin' expensive. I paid £20 for a sack of Ford coil packs, leads, sensors from the scrappy.

Although my flapper manifold is currently drilled for LPG, I do have concerns that the injectors are not readily available when they pack up

Again - how often do injectors pack up? And, with MS, if you can't find the right injectors you can plug pretty much anything in there and just re-calibrate the fuelling to suit the new flow-rate. It's even got a menu option to do it automatically.

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Although my flapper manifold is currently drilled for LPG, I do have concerns that the injectors are not readily available when they pack up

Again - how often do injectors pack up? And, with MS, if you can't find the right injectors you can plug pretty much anything in there and just re-calibrate the fuelling to suit the new flow-rate. It's even got a menu option to do it automatically.

I thought the plug holes in the manifold were different sizes for the different injectors. Are they all the same then? If so, then certainly not worth changing.

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Most injectors mount the same, there are detail differences but the hole they drop into is almost always identical. As an example, my manifold is 3.5 but my injectors are 3.9. The 4.6 manifold is the same, the Thor one uses the same base with a bunch-of-bananas top bolted on instead of the phlegm chamber.

The 3.5 injectors have silly hose tails crimped to the top (yuk) which is not so common, swapping for 3.9 injectors and fuel rail, where they're clamped in place by the rail, is a far more common setup and allows you to pinch injectors from a vast number of cars should the need arise. The 3.9 injectors were used all the way to 4.6 and on Jags and probably numerous other BL/Rover cars.

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Fridge,

Were abouts am i looking on an injector for its part / model number so i can get the flow rate from....

http://users.erols.com/srweiss/tableifc.htm

would i need to remove it to see it?

I have the 3.5 ones that you mentioned earlier with the pipe feeding it from the fuel rail.

Dont suppose anyone knows the actual flow rate of these bad boys?

My base map engine constants were slightly wrong and i wnat to confirm that the injector characteristics are correct b4 i do too much more.

So far i have steady idle at about 800rpm and 14:1 AFR... a little rich.

What AFR am i aiming for at idle? iv heard people go lean here. Things tell me to go 14.7:1

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Were abouts am i looking on an injector for its part / model number so i can get the flow rate from....

Flapper:

post-21-1218064532_thumb.jpg

3.9 / Hotwire:

post-21-1218064549_thumb.jpg

Is it a bit bad that I was able to take both of those photos without leaving the carpeted areas of my house? :ph34r:

would i need to remove it to see it?

Depends on your eyesight really, they're pretty small. I'd go for the digital camera method. If you bother at all, that is...

I have the 3.5 ones that you mentioned earlier with the pipe feeding it from the fuel rail. Dont suppose anyone knows the actual flow rate of these bad boys?

18.13lb/hr I believe.

My base map engine constants were slightly wrong and i wnat to confirm that the injector characteristics are correct b4 i do too much more.

Don't worry - the injector flow is only used to define REQ_FUEL, which is basically an arbitrary base value used as a multiplier for all the calculations the ECU does. As long as your mixture is right, and your duty cycle / pulsewidth reasonable, it doesn't matter greatly what the number is. If you are worried, you can use the "Scale VE" tool to correct your entire fuel map in one go if you change the value of REQ_FUEL. You just tell it the old value and the new value and voila! All sorted.

So far i have steady idle at about 800rpm and 14:1 AFR... a little rich.

Err, that's a bit lean for idling.

What AFR am i aiming for at idle? iv heard people go lean here. Things tell me to go 14.7:1

If you're anywhere near 14.7:1 at idle you're too lean. It's really a "suck it and see" thing, I only have a narrowband sensor and it registers fairly rich at idle, I'd guestimate you want to be 13:1 or richer really. 14.7:1 is for cruising under low load/low RPM situations, if you run that lean elsewhere in the map you can do damage.

To be frank, I think you are worrying about nothing - your injectors are fine, you don't need to change them and you don't need to worry about your REQ_FUEL value.

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Cheers Fridge,

Suppose i best go get on with data logging as im driving then and run megalog viewer on it.

Can worry more about idle at MOT emmissions, i mean the bloke got the flapper through eventually lol

In all im totally impressed with megasquirt, its transformed the driveability of it, No more hesitations and it goes like it never used to. Its definately quicker not that i want speed, it needs toning down cause im struggling to keep it on the road :-)

There is absolutely no point in attempting to make a 14CU flapper run right when a few origional loom changes to the Fuel pump relay and diode pack wiring and your away with something abit more dependable.

If you guys want i will post up exactly how i went about modifying the old loom to make your install quicker. Or maybe you plan to go the full wack and make your own loom?

Any ideas on where i can get a 3.9 fuel rail, and injectors? i guess the pressure reg is the same? I want to scrap the Lucarse loom now and make my own with no resistor pack. B4 the lucas loom fails me.....

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If you guys want i will post up exactly how i went about modifying the old loom to make your install quicker. Or maybe you plan to go the full wack and make your own loom?

Any ideas on where i can get a 3.9 fuel rail, and injectors? i guess the pressure reg is the same? I want to scrap the Lucarse loom now and make my own with no resistor pack. B4 the lucas loom fails me.....

Posting up the mods to the loom I'm sure would be handy. to someone.

I picked up a compete 3.9 inlet manifold at Billing for £10, including fuel rail & injectors. Try eBay or the usual traders.

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Posting up the mods to the loom I'm sure would be handy. to someone.

I picked up a compete 3.9 inlet manifold at Billing for £10, including fuel rail & injectors. Try eBay or the usual traders.

Great, I will keep my eyes peeled, im off to the next LRO show in september, I'll check out ebay too

Yer I was abit funny about modding the origional loom incase i couldnt put it back properly if it failed miserably.

Never going back now though :rolleyes:

I mean there are alway people wanting to install Megasquirt but wanting to also be able to put back what they had quickly if the result is not the desired one of it doesnt work properly and they run out of time and need the vehicle for work etc.

Its just getting across that bridge at first then you dont want to go back.... Yes the grass really is greener on the MS side

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