MG ZR 1.4 hunting idle / K Series
Discussion
so I bought another mg zr, we already have one, a mk2
seller had replaced head gasket
on driving it home, it was chugging/hunting at idle in traffic, and it used loads of fuel
I disconnected the front lambda and it ran great and idle was better too, I had this with the other ZR so ordered a new lambda.
discovered that it had no thermostat, so that was installed during the week
new lambda arrived, put it in
connected back up and its still chugging / hunting at idle
don't know what to look at next, and the earache has started from the mrs so I need it sorting!!
this pic shows some of the various sensors
1. inlet air sensor? if I unplug this with engine running it stalls
2. ?? if I unplug this when engine running nothing changes
3. throttle position sensor. if I unplug this with engine running it idles high and constant
4. and 5. temp sensors, theres two of them but the plugs are different and cant be wrongly plugged in, unplugging them when engine running makes the temp gauge stop working, and the fan come on
6. lambda sensor, new
7. cam shaft sensor, unplugging when engine running doesnt seem to change anything, I had a spare one so swapped it, no different.
engine light isnt on, no fault codes, no pending fault codes. [engine light was on when running with lambda unplugged, but thats cleared now, I have my own reader]
since the lambda was fitted the engine is better on fuel when driving, but idle is shocking
cam belt timing?
HELP!!!
seller had replaced head gasket
on driving it home, it was chugging/hunting at idle in traffic, and it used loads of fuel
I disconnected the front lambda and it ran great and idle was better too, I had this with the other ZR so ordered a new lambda.
discovered that it had no thermostat, so that was installed during the week
new lambda arrived, put it in
connected back up and its still chugging / hunting at idle
don't know what to look at next, and the earache has started from the mrs so I need it sorting!!
this pic shows some of the various sensors
1. inlet air sensor? if I unplug this with engine running it stalls
2. ?? if I unplug this when engine running nothing changes
3. throttle position sensor. if I unplug this with engine running it idles high and constant
4. and 5. temp sensors, theres two of them but the plugs are different and cant be wrongly plugged in, unplugging them when engine running makes the temp gauge stop working, and the fan come on
6. lambda sensor, new
7. cam shaft sensor, unplugging when engine running doesnt seem to change anything, I had a spare one so swapped it, no different.
engine light isnt on, no fault codes, no pending fault codes. [engine light was on when running with lambda unplugged, but thats cleared now, I have my own reader]
since the lambda was fitted the engine is better on fuel when driving, but idle is shocking
cam belt timing?
HELP!!!
Definitely check the cam timing, they do tend to hunt if this is out.
An air leak will also cause this problem. A favorite is the inlet manifold gasket if it either wasn't changed or was badly fitted when the head gasket was done. Also check that all vacuum hoses are connected and that there are no splits etc.
An air leak will also cause this problem. A favorite is the inlet manifold gasket if it either wasn't changed or was badly fitted when the head gasket was done. Also check that all vacuum hoses are connected and that there are no splits etc.
I took inlet manifold off when I put a thermostat in as it provided more room to work, I think the inlet manifold gasket was the original one, or that the manifold had been left bolted to the head when the HG was changed, and it looked suspect so I changed it myself and took care when fitting the gasket and bolting the inlet back on.
There was all manner of bodges, missing heater pipes, water pipe on back of engine not bolted on, broken heater hot/cold valve, snapped bleed screw [dunno how the seller had bled the system!], so if the timing was out I would not be surprised at all.
There was all manner of bodges, missing heater pipes, water pipe on back of engine not bolted on, broken heater hot/cold valve, snapped bleed screw [dunno how the seller had bled the system!], so if the timing was out I would not be surprised at all.
so I was going to swap the temp sensor from our other car today but got to it with a spanner and it would have taken longer than I thought it would
so thought I would look at the cam timing via the belt
well I think I have found the problem, can I have other opinions please? - I put a ruler across to show that I could not line up the marks which to my mind should mean the ruler/straight edge goes through them all and the centre of the bolts - ?
so thought I would look at the cam timing via the belt
well I think I have found the problem, can I have other opinions please? - I put a ruler across to show that I could not line up the marks which to my mind should mean the ruler/straight edge goes through them all and the centre of the bolts - ?
I am not sure what position it was in at the crank, the mark was facing upwards though and I have shuffled the car forward and back by hand with it in 4th to see where the marks were, I know it needs altering so when I get to do the job I will make sure all the marks are lined up right.
I'm not sure it does need altering, which is why I asked. If the timing marks on the crank were aligned in the first picture then it may be fine. If the crank timing marks were aligned in the rest of the pictures, then it's definitely wrong.
Edited by Mr2Mike on Tuesday 2nd December 17:58
The inlet cam is advanced by one tooth and the exhaust is retarded by one tooth. Get the engine to 90BTDC on cylinder one,chec it is correct by measuring the height of Pistons one and two via the plugholes, when they are level you are at 90BTDC. Then align the timing marks on the cam pulleys correctly.
Dave
Dave
Edited by DVandrews on Tuesday 2nd December 17:39
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