antlee928

Ok, where to begin.

I have just completed (Wednesday) coolant drain and refill and also replacement
of a faulty heater valve - rubber diaphragm split. Can this cause a small vacuum
leak? Since changing it the recirculating flap now works. It wasn';t previously.
Anyway, everything seemed ok. No problems with idle or normal driving
performance.

Oh, also got the aircon checked and re-charged (that's how I discovered the air
recirc flap was failing to operate (close) ). Aircon works really well now!

So headed off with #1 son for a short fishing excursion down to Venus Bay
(Victoria. Car felt fine. Again started ok, no idle issues, performance fine. We
stopped near Cranbourne for fuel (BP Ultimate) - gauge was showing about 1/4
tank remaining and filled to top with around 50-60 litres. Car fired up ok,
idling ok and off we went. We stopped on the way at Cowes on Phillip Island
where there was a Hot Rod and Custom car show and had a poke around at some
rather nice machinery. Had lunch, back to car. Fired up ok, idled ok and off we
went. No problems thus far. Everything seemed fine.

On the trip down we were mainly observing posted speed limits but did give it a
stretch on several quieter sections. Car performed perfectly.

We arrived in Venus Bay by which time I noticed the following low/slow speed and
idle symptoms:

1. At idle it would intermittently feel like a very lumpy V8 cam idle

2. Dawdling along at just about/above walking pace the car was lurching forward
in time with this lumpy cam symptom;

3. Whilst stationary it cut out once or twice.

At speed and on the highway it showed no symptoms or ill affects.

We parked went fishing for around 4 hours (caught nothing BTW). On return the
car (cool to cold) would fire but not idle. Tried unsuccessfully around 3-4
times. Ended up having to apply a little throttle for around 15-20 seconds
afterwhich it would seem to idle as normal. As we drove thru the small town of
Venus Bay I again noted this intermittent "lumpy cam" condition and then it
would disappear. We did put the aircon on and briefly noted that it seemed to
disappear. However later testing disproved any apparent relationship.

We arrived home. Again at speed (again some period of more spirited driving)
there seemed to be no ill affects or symptoms. Normal highway speed driving.

So today #1 son and I decided we would go get something for dinner from the
South Melbourne markets (great markets BTW for those Land Sharkers who live in
and around Melbourne). The car would fire up but fail to idle there would be a
very brief moment of ignition then it would stall. Again repeated attempts
failed to get idle yet each time firing. Again a small amount of throttle was
required for approx. 15 seconds to get the car to maintain idle. Sop I decided
to allow the car to warm up to normal operating temperature. During this period
it stalled twice - once at near normal operating temp. I grabbed my PC with
Theo's diagnostic software to check for any faults and some of the snesors - in
particular the idle control valve. No faults in LH or EZK and idle control valve
seemed ok although quite difficult to hear activating (I have my suspicions). So
given the faulty heater valve (rubber diaphragm split - guessing this is cause
for a minor vacuum leak??) I thought I would do an idle adaption using Theo's
software. Completed ok. Restarted car. Seemed ok so off we went to the markets.
However fairly shortly into the trip I again (briefly) experienced this "lumpy
cam" condition. It went away and reappeared (in a milder manner) during the
trip. Again only momentarily. Again normal speed and driving felt OK.

On arrival home I left the car to cool down and later in the afternoon decided
to check again. Again several start fire and stall attempts requiring some small
throttle to get to idle. Now here's where it's gets a little more interesting. I
noticed that it would idle for a short period then stall. Each time the idle
periods prior to stalling seemed to be similar. By this time the car was up to
normal operating temp (fan kicking in). So I decided to time the idle periods
prior to stalling. Based on four tests the engine would fire, idle then stall
after 1 min and 15-17 seconds. It did this consistently over four timed tests.

So this leads me to think that something is happening (a valve opening/closing,
or something electrical/electronic) that is happening after start up after
approximately 75-80 seconds. I performed this test with auto in P and also N -
thinking there might be the condition could in some way be linked to auto
tranny.

Auto feels like it is shifting ok but have not done any specific tests and the
mixed driving conditions from yesterday and today did not cause me to be
suspicious of the auto.

The only other thing I have noticed when experiencing this "lumpy cam" condition
is that when applying throttle there seemed to be a mild/brief lack of throttle
response. Barely noticeable.

So the $64M question is, what can it be? Where do I start to look?

I have suspicions about the actual condition of the idle control valve and
believe it is the original unit.

Over the the forum for some guidance and informed commentary.

Thanks in advance.

Cheers
Tony - S4 with lumpy cam ;-)

Leon Speed

Hello and welcome to the forum!

Some possibilities to consider:
- sticking idle valve
- leaking injectors
- bad ground points (battery strap, engine strap)
- bad fuel pump
- coils and spark plug leads
- false air/vacuum leak (e.g. air injector pump hose to underside air box)

It will be helpful when you add your model year to your signature (in user CP). And pics! We like pics

Mrmerlin

first i would clean the battery terminals and the chassis grounds
clean the hot post and 14 pin connector.
Inspect the CE panel for corrosion look above the panel at the blower box ,
see if you find water drip tell tales,
Clean the fuses, clean the relays ,
any relay thats corroded should be opened and inspected ,
clean the internal contacts and smell it for burning
check the voltage of the alternator at the hot post at 1500 rpm
remove both ignition coil wires check the ends for corrosion
make sure the grounds are both connected to each coil and engine mounting point.
remove the vacuum lines on each fuel damper and the FPR smell for gas,
any fuel smell means a leaking part, replace it.
Refit a fresh MAF as yous may be ready to rebuild.
Report back

Hilton

Hi Tony,

Some questions:

First - if you fold back the passenger seat carpet, there's a clear relay tucked off to the back left of the footwell against the ECU's (its attached to the bracket that holds the ECU's). Is there a green or red LED shining in the body of the clear relay? (its the Ignition Monitoring System if you want to search for info - yours is an 89 IIRC? 87/88 and non-cat cars don't have it).

Second - how old is your Mass Airflow Sensor? (aka MAF) And have you moved it recently?

Third - how old is your O2 sensor? The timing is about what I'd expect for switching from open to closed loop as the sensor heats up, so this would be one of the suspects.

The possibly range of causes is fairly broad - I have a similar issue with my 89 and have been mulling possible causes (although in my case its probably caused by someone leaving the passenger door open, outside, in the rain, all night, after letting our 3yo sit in the car ).

The "lumpy" feeling is most likely one ignition bank not working - possible causes off the top of my head are (in no particular order):

• O2 sensor signal not working, so fuel is wrong, which sets off the ignition monitoring system due to exhaust temperature sensor readings on that bank.
• Loose/corroded plug wires, especially from coil to dist caps
• MAF signal intermittently out of range, causing the car to default to "limp home mode" (very rich condition with set injector opening time) - again setting off the IMS relay. Could be caused by something like exposed MAF wires in the connector boot.
• Faulty Temp II sensor
• Dying ignition amplifier (pair of transistorised units under the plastic cover at front-left of car just under the bonnet)
• Corrosion in ECU connectors
• Loose/corroded grounds (have you cleaned all the grounds yet? should be on everyone's list of preventative maintenance)
• Intermittent short in one side of the injector harness (there are two injector circuits - 4 per side)

My suspicion is the O2 sensor wiring - its near the center console and in the vicinity of the work carried out on the AC diaphragm, so could easily have been disturbed during the work. (O2 sensor harness runs along the bottom right of the fuse panel and out through a rubber grommet just behind the right-side of the wooden cover (RHD car for those LHD owners wondering WTF I'm on about ).

Unfortunately - its going to take a lot of troubleshooting to eliminate other possible causes and make sure its actually fixed, before you can be confident driving it.

antlee928

Hi Hilton, Ok my car is an S$ MY89. Given the observed and consistent failure after approx. 75-80 seconds I am guessing it has to be something that is switching on or switching off after ignition. This problem has only surfaced since the very recent work e.g. X-pipe and hi floe cat fitment, aircon re-charge, heater valve replacement, etc. Whilst a few have suggested ground points, loosed/corroded plug wires, ECU connectors, etc. I am gravitating towards the O2 and maybe MAF issues. When changing x-pipe I had to remove and reinstall the O2 sensor. I managed this without disconnecting at connection point near fuse box. I am wondering if I have managed to "stretch" this connection so that it is now partially of fully disconnected (worked it's way loose after a long run). This sounds like the most logiocal explanation given that the car now stalls everytime and consistently after approx. 75-80 seconds. BTW, when idling during thgis period it appears to idle ok and not lumpy. If MAF then I would have thought this would also affect normal higher speed driving and would also cause the car not to fire or idle at all, OR to consistently lumpy idle. I will check the O2 sensor connection and report back. Cheers Tony

John Speake

The "igntion protection relay" has a nominal delay value of 18 seconds, so that doesn't sound so likely, but the acid test is to check for either red or green delay after that period.

Try doing a battery ground disconnect, unplug the O2 sensor at that round rubber connector on the floor infront of the CE panel, then reconnect battery, and fire up the engine, see if it runs better.

Leon Speed

Since the symptoms occur cold as well as hot, it is more likely to be the temp II sensor than the O2 sensor if it is mixture related. Then again, focusing on one idea might lead to blindness to other causes, so it is better to cover all bases.

Stromius

I would also have a close look at the connectors for the Temp II, MAF. The boot can hide stripped wires that can make the components looks suspect when the wires touch. The coil connection immediately under the 14 wire post also can hide corrosion. Easy, cheap stuff first!

Welcome!!

TheoJ

hi,
just a hunch, try swapping the MAF. It happens that the MAF power stage gets disconnected from the heat sink and heats up which goes into full conduction after a minute or so. That results into full output causing the LH to over fuel the engine.
Since you have a UDT999 tool you should be able to connect to the LH with the engine running and monitor the MAF output in real time. It is normal that the engine runs poorly while talking to the diag bus but it keeps running. If you suddenly see the MAF go to full output after 70 secs you found the cause.
The MAF can likely be rerpaired.
regards
Theo

antlee928

Hi Theo, Have just run the diagnostic software and can report as follows:

1. Still same cold start issues and having to hold some throttle for about 15 secs to get to idle from cold.
2. Engine cuts out after approx, 75-80 secs
3. I have unplugged and plugged the O2 sensor connection, the LH and EZK ECU connectors.
4. I have checked all relays and fuses - all seem ok
5. The IMS relay does not show any LED shining (is this normal??)
6. LH info as follows: Ver L01LH-JET, Info1=92861812313, Info2=0280002507, Info3=2287356487
7. Check Faults shows no recorded faults with LH or EZK
8. Noted that engine did not stall whilst diagnostic software connected and measuring values. Hmmm???
9. Values at end of test (after about 5 mins or so engine running and checking and re-checking values:
ETemp=79deg
Vbat=12.62V
Vref=4.08V
Ezk-on=13.29V
MAF=0.37V (at idle)
RPM= varied between mid 500s to around 640rpm at idle
OXY = shows full bar of blue up to R indication

So my quick analysis of this is that MAF seems to be ok however O2 sensor looks like it is stuffed. Your thoughts and comments please.

Cheers Tony

antlee928

HI Hilton, refer my message just sent to Theo Jenkinson following some checks using the UDT999 diagnostic software:

1. Still same cold start issues and having to hold some throttle for about 15 secs to get to idle from cold.
2. Engine cuts out after approx, 75-80 secs
3. I have unplugged and plugged the O2 sensor connection, the LH and EZK ECU connectors.
4. I have checked all relays and fuses - all seem ok
5. The IMS relay does not show any LED shining (is this normal??)
6. LH info as follows: Ver L01LH-JET, Info1=92861812313, Info2=0280002507, Info3=2287356487
7. Check Faults shows no recorded faults with LH or EZK
8. Noted that engine did not stall whilst diagnostic software connected and measuring values. Hmmm???
9. Values at end of test (after about 5 mins or so engine running and checking and re-checking values:
ETemp=79deg
Vbat=12.62V
Vref=4.08V
Ezk-on=13.29V
MAF=0.37V (at idle)
RPM= varied between mid 500s to around 640rpm at idle
OXY = shows full bar of blue up to R indication

So my quick analysis of this is that MAF seems to be ok however O2 sensor looks like it is stuffed. Your thoughts and comments please.

Cheers Tony

NC928S4

Check this thread out too "Recurring Low Idle - Low Power - Pistol is loaded" It was very valuable to confirm what was actually working according to spec. Search for the string below. I couldn't figure out how to send the actual thread...

Recurring Low Idle - Low Power - Pistol is loaded

TheoJ

Hi Tony,
so the MAF output does not go to max when the problem occurs? Fine. MAF probably ok.
To check the operation of the O2 sensor you need to rev the engine to about 2000rpm and then quickly let off the gas. It should show the O2 reading briefly go from R to L as described in the manual. This verifies the operation of the circuit in the LH and the Lambda sensor itself.
Disconnect the O2 and see if the problem remains. The LH will ignore the missing O2 sensor and go into a pre-programmed loop.

The LED's at the IMR should be off and remain off. In case of doubt, make a bridge wire and connect the 12v directly to the injectors, thus eliminating the IMR. Check this out: http://jenniskens.livedsl.nl/Technical/Tips/4/MyTip477.htm

The lumpy feeling could also be caused by ignition problems at the coil or distributor. Common problem is a loose ignition wire that connects the coil.

regards

antlee928

Hi Theo, Ok so this is where I am at with this problem.

1. I have disconnected and reconnected LH and EZK connectors - no difference to problem;
2. I have checked for any vacuum leaks and none obvious;
3. Removed airboxx and filter to check for any vacuum hoses that may have come loose since I had only replaced the heater valve 2-3 days ago. Nothinh obvious all seemed ok;
4. It was suggested to disconnect the MAF and start car. Did this and car ran much worse. Reconnected the MAF and started car. Surprise, surprise! Car appeared to idle after initial start/fire stall issue then ran fine until and including normal operating temp. There was no stalling after 75-80 seconds as previously and consistently noted. I then noticed the O2 sensor was disconnected so reconnected. Within a short period the intermittent lumpy idle returned (not as bad mind you) and also noted some mild misfire in exhaust note. Disconnected the O2 sensor again and the poor idle disappeared.
5. Idle seemed smoother although a little higher. Reassembled air box in stages with engine running. No change or idle issues.
6. Air box fully reassembled then reconnected the O2 sensor only to find within a short period the intermittent lumpy idle (not as bad though). No stalling experienced.
7. Took car for a run with some high speed stuff with no problems.
8. Am resigned to replacing the O2 sensor. It appears to be the original unit and there is no record in the service notes that I have that it has ever been replaced ( they normally don't get replaced and typically wear out, reduce in performance or simply straight out fail). So a fresh O2 sensor is in order.

I will keep the list posted on any new developments and results of the O2 sensor replacement.

Cheers & Thanks to all who assisted.

Tony
S4 MY89 Guards Red & better idle! :-D

TheoJ

hi, could a bad or corroded contact at the MAF connector have contributed to the problem?

Ok, the car should run better with the O2 connected, and reasonably well with the O2 sensor disconnected. Did you see the O2 reading respond when using the UDT999 tool to test the lambda sensor? It should respond. if it doesn't you might have a faulty LH circuit.
Any chance you borrow a known good LH and test before replacing the O2 sensor?