High CO / Poor hot starting

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High CO / Poor hot starting

Postby nhaynes » Sat 30.05.2015, 10:40

Hi all, apologies for starting another thread but my prior posting seems to have been amalgamated with others and now the original issue is somewhat jumbled with others. I'll summarise my last 3 postings followed by latest info. If anyone has any recommendations, as ever, I would welcome them.

I have a 1992 Elan SE (no CAT, open loop) which has high CO above 4% (versus 3.5% max). Also, starting when hot is tricky and normally requires several seconds to fire. Starting from cold is very good normally firing within a second. The exhaust smells rich.

I'd appreciate some help as I've already completed some preliminary adjustments: I've adjusted the CO pot, the small blue box adjacent to the Engine Control Unit (ECU), whilst being hooked up to the MOT exhaust gas analyser. I did this with a paperclip in the A and B ports of the ALDL so the car was in CO adjust mode as per the Lotus Service Notes and WikiLEC. Adjusting the CO pot screw made no difference to the CO values. They went up in one direction but would not come down below 4%. Is this due to being at the end of the potentiometer range? I checked the ECU and it still has the original Lotus seal in tact. I'm loathed to break the seal to change the CO PROM but maybe this is the only way to get the CO down? I'm running fairly old spark plugs and air cleaner, last change 4,000 miles/3 years ago so should probably check these.

I've gone and checked stuff I've done since the last MOT. All plugs are ok with 0.031" gaps. Air filter still looks new. Oil level was too high, over the max fill mark. I've removed 0.7L. I do wonder if this was pulling through the crankcase breather system and contaminating the exhaust gas. I can check again on the MOT tester and see if it's made any difference. I did change the coolant last year and noticed a change on the temp gauge but can't believe this is the cause. I'm also now running on a full tank of new fuel. I'd be interested to know if anyone else has adjusted the CO pot and whether adjustment one way (anticlockwise) reduces CO and the other (clockwise) increases CO or whether there is a sweet spot and lots of spare travel. If the latter I have lost the original setting so will need to find the sweet spot again. If I adjust without the exhaust tester, would you expect to hear a change in engine note when you find the sweet spot for CO on the potentiometer?

Got the Elan back on the exhaust gas analyser again, no significant difference since last time. The results I got are:
CO: 5.04%
Lambda: 0.899
CO2: 11.1%
HC: 150ppm
O2: 1.12
I'm thinking the engine should be running at stoic (Lambda=1) so Lambda = 0.899 certainly proves I'm running rich or don't have enough air. It still starts poorly when hot but first crank when cold. I changed the cam belt back in May 2013 and thought I'd got the base timing spot on but now I'm questioning whether I should re-check. I don't have an emission reading for the MOT last year so maybe it was missed after the belt change. I need to get or borrow a strobe timing light before I can check the base timing again. I've tried all the simple stuff so base timing, injectors or coolant temp sensor are now in the frame.

I've tried disconnecting the Coolant Temperature Sensor (CTS), not to be confused with the fan thermal switch and the temperature gauge sender which are all located on the same aluminium cooling housing. If the CTS is malfunctioning, it may be causing incorrect air fuel ratio (AFR). The CTS is a negative thermistor so at high temperature reads low resistance and at low temperature reads high resistance. Disconnecting the CTS tells the ECU that the resistance is high thereby implying a cold start. Unfortunately the CTS connector is right under the Cam Angle Sensor (CAS) so tricky to remove. Do I need a special tool to unclip the CTS connector? I don't want to break the connector!

I've now run the car at idle for 30 mins (not in service mode) and then removed and checked the spark plugs:
Cylinder 1: Heavy soot
Cylinder 2: No deposits
Cylinder 3: Heavy soot
Cylinder 4: No deposits
Now wondering whether I have leaking/faulty injectors on cylinders 1 and 3 or whether there's a fault with the injector driver circuit. The injectors are driven from the ECU, injectors 1 and 3 on one circuit and 2 and 4 on another. Not sure how to test the circuit.

Sorry for the wordy posting, replies to my questions above would be greatly appreciated.
Thanks,
Neil.
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Re: High CO / Poor hot starting

Postby GeoffSmith » Sat 30.05.2015, 11:17

nhaynes wrote:I have a 1992 Elan SE (no CAT, open loop) which has high CO above 4% (versus 3.5% max). Also, starting when hot is tricky and normally requires several seconds to fire. Starting from cold is very good normally firing within a second. The exhaust smells rich.
.
.
.
I've now run the car at idle for 30 mins (not in service mode) and then removed and checked the spark plugs:
Cylinder 1: Heavy soot
Cylinder 2: No deposits
Cylinder 3: Heavy soot
Cylinder 4: No deposits
Now wondering whether I have leaking/faulty injectors on cylinders 1 and 3 or whether there's a fault with the injector driver circuit. The injectors are driven from the ECU, injectors 1 and 3 on one circuit and 2 and 4 on another. Not sure how to test the circuit.


Probably not what you want to hear, but all the evidence suggests a problem with the ECU drive to 1 & 3. If you have a DVM, I would first try and check the voltage at the injectors with the ignition on and then with the engine running - they should all be similar, but I suspect you will find 1 & 3 high. It may be due to either 2 or 4 being low resistance, dragging down the drive to 2 & 4 and these two running lean, but this does not fit with high CO readings and cold starting unfortunately.

If you haven't got a DVM then you could swap injectors (1 & 3 with 2 & 4) and run for 30 minutes again to see if the sooting changes to 2 & 4.
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Re: High CO / Poor hot starting

Postby Steve_P » Sun 31.05.2015, 10:12

Hi Neil, I've had high CO in the past, it's certainly worth checking the injectors as Geoff suggests - some things I would also check:

1) Make sure that the base timing is set correctly.
2) Check that there are no air leaks from any rubber tubes connected to the inlet manifold.
3) The revised PROM available from Lotus is worth fitting as it gives a wider CO adjustment range, with the new PROM (on my car) there was a very small window of adjustment when the CO value was correct - past which it went very high or very low. So there is a very small sweet spot, however I can't remember for sure which way was rich but my feeling is clockwise as you suggest - when you find the pot's spot the engine clearly changes its sound over a very small adjustment between rich and lean, when hardly turning
the pot!
4) Worth checking for any ECU error codes if you have not already done so.

Good luck, Steve
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Re: High CO / Poor hot starting

Postby nhaynes » Sat 06.06.2015, 13:27

I've replaced the vacuum hose to the fuel pressure regulator as the retention force was very low. The clamps were not having any effect. I've purchased a thicker wall vacuum hose that has a higher retention force on the spigots (Also changed the boost gauge pipe which was really badly perished). I'm not sure the pipe was leaking vacuum but would be interested to know the effect if it was. I've checked the spark plugs again after a 30 minute idle and they seem better (but maybe it's just me). The is no new soot build-up on 1 and 3, see attached pictures. I'll have to purchase a set of new plugs to be really sure but I'll do this anyway.
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Neil.
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Re: High CO / Poor hot starting

Postby Ian T » Thu 25.06.2015, 15:22

Have you fixed this yet Neil?

I have a very similar situation, with just one plug staying clean. Very rich idle, I think the readings from the gas tester were similar.

Cold start (after leaving it for a week) is instantaneous, but re-starting cold or warm takes several seconds to go, then will run on 2-3 cylinders for a short while if you don't blip the throttle.

Pulling the plugs after a start shows 1, 2 and 4 are black and wet with fuel, 3 is clean and dry.

If I drive my car for a while, bring it home and switch the engine straight off, pull the plugs, they are all about the same - not too black, certainly not white.

I therefore deduced the problem was only there at idle and so started going through vacuum leaks, replaced the intake manifold gaskets after replacing the injectors with new ones. I'm pretty confident I don't have a vacuum leak, but given I haven't stripped the injection loom apart, I don't know for sure that injector no3 has a good earth for example. I'll have a look.

I'd be interested to know how you get on with yours, as we seem to have similar symptoms.

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Re: High CO / Poor hot starting

Postby lotusguymichael » Tue 29.09.2015, 00:10

I had this same problem last week. I had been overhauling the transmission with new syncros and some seals, and rebooting the axles. The car started up fine after 4 months of down time and ran great for a 50 mile run. I shut it down and then restarted it, and it seemed like it was running on only 2 cylinders. I had no CEL codes. I suspected that fuel injectors were the problem after eliminating ignition from the trouble shooting check list. I pulled the plugs, and had the same soot on plugs 1 and 3 as your pictures show. After a chat with LotusGirlMarie, I ordered a set of injectors from this listing on ebey...

http://www.ebay.com/itm/191637275013?it ... m=&vxp=mtr

They were overnight shipped from AZ and in the car last Friday night. The difference was amazing.

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Re: High CO / Poor hot starting

Postby GeoffSmith » Tue 29.09.2015, 11:29

:agree: With two pots down in even and odd grouping, the problem is fuel whereas if they total five (1&4 and 2&3) then the problem is electrical. If one injector goes low impedance, it drags the other (good?) injector down as the drive circuit is common.

I would first diagnose exactly what is faulty by pulling the drive to the injectors in turn and see how she runs:

Improvement - bad one
No change - the one that is paired with the bad one
Worse (x2) - good ones

If there are two that show no improvement then the problem probably lies with the ECU drive or wiring.
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Re: High CO / Poor hot starting

Postby nhaynes » Sun 01.11.2015, 18:55

Hi Jeff,
Thanks for your helpful diagnostic suggestions, sorry it's been a while for my reply. I've managed to disconnect the injector harness connections for cylinders 2 and 3. Getting that little retaining spring out and back in again is tricky with the intake plenum in situ. I was afraid of losing the spring so I left cylinders 1 and 4 for now as the access is more restrictive. Removing the injector harness connector on cylinder 2 caused a much rougher idle, the same for cylinder 3. I suspect this points towards the ECU, as I would have expected cylinder 2 to make idle worse (good spark plug) and cylinder 3 to make idle better (sooted spark plug). Maybe you could give some more feedback Jeff. Is there an easier way to pull the injector drivers than disconnecting the harness connector? Should I buy a set of new injectors as there is currently a set of OE Delphi ones on ebay.
Thanks,
Neil.
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Re: High CO / Poor hot starting

Postby nhaynes » Sun 03.04.2016, 20:17

Hi everyone. It's time to get the Lotus MOT again. I've invested in a Gunson Gastester so I don't have to spend hours on my neighbour's MOT tester. I've got the CO down to <3% from a 7% high. The CO pot is at the end of its anticlockwise travel (clockwise adjustment increased CO) so I then looked at the base timing which was at 14% advanced. Adjusting base timing to the recommended 16% made almost no difference but by retarding the timing to 0-5% retarded and adjusting the idle on the idle speed screw on top of the throttle body gets me in the CO box at <3%. So, I can get through the MOT but wonder why I've had to adjust Base timing so much. I plan to adjust back to correct base timing once I'm through the MOT. I have the original ECU with original seal so am wondering whether I should get the CO chip update which gives greater adjustment on the CO pot. Failing this, not sure what else to do, maybe invest in a new set of injectors and get the current ones cleaned. Any comments?
Thanks,
Neil.
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Re: High CO / Poor hot starting

Postby John_W » Mon 25.04.2016, 08:18

Neil,
If you have an early SE and still have the original chip, you'll probably have difficulty achieving the emissions targets. That's why Lotus issued new chips when the emissions regs were changed. There's a Service Bulletin about it around somewhere.

Base timing should be 16 deg BTDC as you say, and a good spark is needed (31 thou gap). Until August 2005 my car was running on its original chip ( a "9239" PROM id) and although it passed the MOT emissions OK, the CO potentiometer had no adjustment left. Since changing to the latest version of the Lotus chip (a "9930") on which all of ElanScanMan's Mountain chips for the SE are based, the emissions are lower and there's still about half a turn of adjustment available on the CO pot. You can check the PROM id on ElanScan.

The replacement chip may still be available from Lotus. If not it's a good excuse to put an Everest in which based on the latest Lotus version.

John
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Re: High CO / Poor hot starting

Postby nhaynes » Thu 15.09.2016, 17:17

Update on my Elan. Along with running rich and high CO, I've now developed a misfire. I've changed the plugs and plug leads and still the same, so I think I can rule out the ignition system. I've exchanged ECU's with another Elan and the misfire does not transfer with the ECU so I think I can rule out the ECU injector drivers. I've completed a pin check between the injector connectors and ECU pins and the harness is ok so can rule out the harness. I briefly got rid of the misfire when I jiggled the No 1 injector connector.

I've completed the following diagnostics:
Removed new spark plugs, they've run for 10 mins max, see attached picture:
Plug 1: heavily sooted
Plug 2: heavily sooted
Plug 3: Clean
Plug 4: heavily sooted

I measured the resistance across the fuel injectors and recorded the following:
Injector 1: 1.57 ohms
Injector 2: 2.29 ohms
Injector 3: 2.29 ohms
Injector 4: 1.92 ohms

I then reconnected the injector connectors and observed the following effect to misfire when pulling individual injector connectors:
Injector 1: Better
Injector 2: Worse
Injector 3: Better
Injector 4: Worse

I then measured voltage across injectors 1 and 3 as 0.07v and 0.03v respectively.

I've ordered a new set of injectors as I believe No 1 injector is probably faulty and is drawing down No 3. I'd appreciate anyone commenting on what the injector resistance should be and providing any further diagnostic comments. Jeff, if you are reading this, I'd really appreciate your comments.
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Thanks,
Neil.
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Re: High CO / Poor hot starting

Postby Brit-Car-Nut » Thu 15.09.2016, 19:28

I just measured a set if NEW ones (from the eBay listing: http://www.ebay.com/itm/191637275013) and they are all 2.2 ohms

The ignition (spark) and injection (fuel) fire Two Cylinders at each cycle. The ignition fires 1- 4 and 2 - 3 while the injectors squirt 1- 3 and 2- 4

Since 1, 2 and 4 are sooty, it is possible # 3 injector isn't working at all?
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Re: High CO / Poor hot starting

Postby Danevansgolf » Thu 15.09.2016, 23:43

Hi have also just received and fitted the same injectors, as above. Everything works well, except, under heavy acceleration the car decides to splutter, and it feels like there isn't enough fuel getting to the car??? During normal light acceleration the car is fine
Going back into the garage of headaches to figure it out.. Am lost!!
Please keep this thread going , as I also need to know how things turn out. Like wise I will update with my progress, and if any of you have ideas , please let me know..
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Re: High CO / Poor hot starting

Postby Brit-Car-Nut » Fri 16.09.2016, 02:32

Fuel Filter? Fuel Pressure Regulator? Tired Plug Wires? Tired/Weak Ignition Coils?

Possible but less likely: Clogged Exhaust? Tired/Wrong Fuel Pump? Obstructed Intake Circuit?
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Re: High CO / Poor hot starting

Postby HJ2 » Fri 16.09.2016, 09:04

Did you check all the bond straps (ground connections) that are involved in the ignition sequence?
Sometimes these work themselves loose, resulting in odd behaviour.

Are you sure that the plug gap is set to 0.8 mm? From the pictures it looks more like 1.1 mm (but it is hard to say :-D )
The behaviour you now have is similar to mine when I gapped the plugs wrong.

I presume the hot start is now instant as well as the cold start with the new injectors?
(I had this problem as well and it was indeed a hanging injector.
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Re: High CO / Poor hot starting

Postby Danevansgolf » Sat 17.09.2016, 23:11

I've just given up, and have gone to see a electronic mechanic. Within of about an hour or so, he has replied and told me the manifold air pressure sensor is f****d.. He unplugged it and the hot starting problem was cured immediately. I will on Monday order a new one. I suggest you unplug yours to see if the hot starting problem is cured (temporally) If so you'll know it's Fooked. I'll keep you all posted on the outcome.
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Re: High CO / Poor hot starting

Postby Brit-Car-Nut » Sun 18.09.2016, 01:00

SORRY EVERYONE. I read the previous posting to say MAT Manifold Air Temp Sensor. I was obviously more tired than I thought when I read this.

This info is for the MAT, NOT the MAP which is probably a SMP AS4, GM 2132832 {#19106759} or AIRTEX/WELLS 5S2406. I say this because a lot of MAPs that were "discovered" had the wrong plug. I used the 1989 I-Mark listing since the Injection sensors all seem to have come from that car. I will dig out the MAP I bought a while ago and verify that it really fits.

EDIT: Oct 4,2016: The AS4 which I ordered via PeterD's posting DOES NOT Fit. Unfortunately, I will have to order a different one because the one I got was not boxed or otherwise marked, so maybe the seller was shipping the wrong part.
I have ordered an AS5 and will go to NAPA when it arrives to see if they have the plug for either and check them that way.

The MAT part # from Lotus is A100E6283F and it is in the price book at £58.34

SJs Lists it for £35.56

It is a VERY COMMON GM part 25037334 which translated to a Standard Motor Products AX1 / AX1T. The AX1T is much less expensive because it is not in retail packaging. They are otherwise the same.

On eBay UK: http://www.ebay.co.uk/itm/Standard-Moto ... Sw6n5Xv3qt

Rock Auto (under Emissions): Use The 1991 Isuzu listing to see both versions of the SMP version . To see more options, use 1987 Pontiac Fiero V6
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Re: High CO / Poor hot starting

Postby Simon_P » Sun 18.09.2016, 16:24

Wouldn't an elanscan have caught this?

It would be good to see the fault on a scan.
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Re: High CO / Poor hot starting

Postby Danevansgolf » Sun 18.09.2016, 22:31

No the elan scan did not pick it up. The sensor is still working, so elanscan doesn't pick it up. I'm not sure what the readings were, but I understand the sensor was outside its perameters, but I will check.. Hopefully I can get a sensor from my local auto spares shop, otherwise it'll be sj or Paul matty..
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Re: High CO / Poor hot starting

Postby nhaynes » Mon 19.09.2016, 10:58

Plugs on my Elan are all set to 0.8mm as should be. I've ordered a new set of original OEM injectors from ebay, see link below. Once received I will fit them and advise if the misfire is fixed. I suspect ECT and/or MAP sensors to be the root cause of the high CO but may also be injector related. Again, I'll send out further postings once I have information to share.
http://www.ebay.co.uk/itm/191637275013
Thanks,
Neil.
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