350i rough on start-up
Discussion
Hi I'm going to describe symptoms here and see what you geniuses come up with!
My '84 FHC is very temperamental on start-up: it catches fairly easily then drifts between barely running and surging- my mechanic knew this when I picked the car up, but since it needed a gearbox re-build we decided to leave it until then. After surging up and down for a while it stabilises, and up until recently this was no big problem because it drove OK when warm. I was told not to apply any throttle and just let it settle (about 1 minute) which was working OK.
But... I was out for a burn and after about 10 minutes of driving the revs died and all I had was tickover. I ditched into a laneway and let it run- applying throttle caused the revs to stay at tickover rate but get very rough (checked the obvious- no broken cable). After a few "re-boots" (the modern "turn it off and on" doesn't work on 1980's stuff!) I decided in my wisdom to tickover my way home with hazards on and see if it fixed itself. After a few 100 yards I decided this was not very bright, so I re-ditched it into a carpark and began to look for a leafy branch to hit it with.
At this stage I noticed a click coming from under the dash passenger side when I applied throttle. It was as if some electrical gremlin was over-riding throttle inputs and cutting the fuel.
Anyhoo after a few minutes of ticking over, it just fixed itself! Just like that. And I drove home fine.
So- any ideas? I need to take it to my mechanic in early Feb for work and I would like to make it, so can I try some fix(es)?
Thanks!!
My '84 FHC is very temperamental on start-up: it catches fairly easily then drifts between barely running and surging- my mechanic knew this when I picked the car up, but since it needed a gearbox re-build we decided to leave it until then. After surging up and down for a while it stabilises, and up until recently this was no big problem because it drove OK when warm. I was told not to apply any throttle and just let it settle (about 1 minute) which was working OK.
But... I was out for a burn and after about 10 minutes of driving the revs died and all I had was tickover. I ditched into a laneway and let it run- applying throttle caused the revs to stay at tickover rate but get very rough (checked the obvious- no broken cable). After a few "re-boots" (the modern "turn it off and on" doesn't work on 1980's stuff!) I decided in my wisdom to tickover my way home with hazards on and see if it fixed itself. After a few 100 yards I decided this was not very bright, so I re-ditched it into a carpark and began to look for a leafy branch to hit it with.
At this stage I noticed a click coming from under the dash passenger side when I applied throttle. It was as if some electrical gremlin was over-riding throttle inputs and cutting the fuel.
Anyhoo after a few minutes of ticking over, it just fixed itself! Just like that. And I drove home fine.
So- any ideas? I need to take it to my mechanic in early Feb for work and I would like to make it, so can I try some fix(es)?
Thanks!!
Edited by General Zod on Saturday 23 January 07:06
Sounds like the fuel pump steering module (red box on the relay panel) is playing up or the connections to it , causing loss or intermittent fuel / pressure. Make sure all the relays are seated properly
Quick test is to get the car running and tap the relays in turn with plastic screwdriver handle
It's normally something simple, do those before rushing off and start replacing bits
Quick test is to get the car running and tap the relays in turn with plastic screwdriver handle
It's normally something simple, do those before rushing off and start replacing bits
Hi mate...It could also just be a loose ECU plug...Try pushing it on firmly and see if it clicks...Could be as Chris say's but Chris you remember my antics with the ECU plug...It showed different symptoms each time..In Belgium it was like the timing was so far out that when you applied throttle it wanted to die but as you take you foot of it picks up...Then i had it cut out when a few of us went to Bodium castle...It did do it going to the bush classic car meet and i nearly got my head run over laying by the side of the car faffing with the fuel pump wires in a dangerous attempt to find it or fix it...Cheers...Ziga
General Zod said:
1.it catches fairly easily then drifts between barely running and surging.
2. After surging up and down for a while it stabilises, and up until recently this was no big problem because it drove OK when warm.
3. applying throttle caused the revs to stay at tickover rate but get very rough
4. At this stage I noticed a click coming from under the dash passenger side when I applied throttle. It was as if some electrical gremlin was over-riding throttle inputs and cutting the fuel.
5. After a few minutes of ticking over, it just fixed itself! Just like that. And I drove home fine.
2. After surging up and down for a while it stabilises, and up until recently this was no big problem because it drove OK when warm.
3. applying throttle caused the revs to stay at tickover rate but get very rough
4. At this stage I noticed a click coming from under the dash passenger side when I applied throttle. It was as if some electrical gremlin was over-riding throttle inputs and cutting the fuel.
5. After a few minutes of ticking over, it just fixed itself! Just like that. And I drove home fine.
Jack Valiant said:
If it is temp related then have a look at the engine temp sensor on the top of the engine
As Chris say's...This does sound synonymous of the CTS...Especially the hunting and then is okay once warm..Also too much fuel delivery will cause the engine to run like crap...As i have an adjustable fuel reg i went through the stage of "Fiddling"...On one occasion i turned up the fuel pressure by 2psi..Making it around 45psi...However whilst travelling at speed on the motorway i noticed each time i went to accelerate the engine wanted to die...Another pointer is that the engine from cold should not start straight away..The engine should spin enough to prime the oil to the top of the engine before bursting into life.
Also re-setting the ECU DOES work but you have to disconnect it from the connector and disconnect the battery for at least an hour...This then discharges any currents from the components.
The "Clicking" should be heard but if its like a rapid succession of clicks then its not good..Relays can stick but they either work or they don't, Its always worth carrying spares..The red "Pektron" steering module can be bought from Rimmers...
Try starting it without the 9th injector connected...(The blue plug on the front of the plenum)..You can also disconnect the CTS which will make it harder to start but should eliminate the hunting and cold start issue..
I wrecked my brain over this for a while, Even replacing the CTS a few times with no change..Then i decided to look at the plug connector to it and found this...
This apparently caused previous owners to spend a fortune in trying to find the fault...One owner spent 13.5K in 6 years on my Wedge..Tower view racing replaced injectors..Thermotime..CTS..Had the AFM rebuilt and re-calibrated...The ECU was rebuilt...And there was 2.5K spent on "Engine work" which probably meant a replacement cam...Then i come along and find a twisted wire inside the rubber boot of the CTS connector...Touch...
SO >>>> PLEASE...PLEASE...PLEASE be methodical with testing and eliminating before going off and replacing parts that do not need changing..This can actually cause more problems and you are no further forward....
The fix is generally simple...
Cheers...Ziga
Fellas I really appreciate all this- thanks for taking the time to write!
I'm going to look into all your suggestions. Just in case it looks like the steering module, is this the right one: http://www.rimmerbros.co.uk/Item--i-DAC1861
And is there a source for the CTS / temperature sensor? Again, just in case I need them. I take on board what you both say about not rushing in to replacing things without being methodical.
I'm going to look into all your suggestions. Just in case it looks like the steering module, is this the right one: http://www.rimmerbros.co.uk/Item--i-DAC1861
And is there a source for the CTS / temperature sensor? Again, just in case I need them. I take on board what you both say about not rushing in to replacing things without being methodical.
So now we have a Zod and a Zig - we just need a Zurg to complete the set!
Going back to your original symptoms - when it's started from cold and hunting, if you don't wait but drive it straight away, what happens - does it cough and splutter, generally OK, or what?
Also let us know if you see excessively sooty exhaust at any time.
As said above - checking connections is free and easy - so do that first, ECU multiplug, sensors (coolant temp sensor, throttle pot, airflow meter) etc.
I had a similar problem with my 350i which turned out to he the coolant temp sensor going open-circuit in the mid-range as it warmed up, you might want to check it with an ohmmeter.
Going back to your original symptoms - when it's started from cold and hunting, if you don't wait but drive it straight away, what happens - does it cough and splutter, generally OK, or what?
Also let us know if you see excessively sooty exhaust at any time.
As said above - checking connections is free and easy - so do that first, ECU multiplug, sensors (coolant temp sensor, throttle pot, airflow meter) etc.
I had a similar problem with my 350i which turned out to he the coolant temp sensor going open-circuit in the mid-range as it warmed up, you might want to check it with an ohmmeter.
adam quantrill said:
So now we have a Zod and a Zig - we just need a Zurg to complete the set!
Hi Adam...There are a couple of brothers you forgot...There was also "Zed" & "Zag"..Unfortunately Zed got killed in Pulp fiction ..Zag is getting on now...Must be well into his 90's..I think he retired to Zog...Also its not a good idea to get us all together as after a few bottles of quality scotch each the singing of rude songs becomes obligatory ...And i mean rude!..
So Zod..Here was the thread as regards to the CTS...Hope this helps...
http://www.pistonheads.com/gassing/topic.asp?h=0&a...
adam quantrill said:
Going back to your original symptoms - when it's started from cold and hunting, if you don't wait but drive it straight away, what happens - does it cough and splutter, generally OK, or what?
Also let us know if you see excessively sooty exhaust at any time.
.
For your first question driving away is impossible. It just stalls or surges forward then stalls. Once running it seems 100% to me. Exhaust looks very clean.Also let us know if you see excessively sooty exhaust at any time.
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