34 replies to this topic

[LukeH]

Hi

I'm in desparate need of some help. I've spent 3 years restoring my 97 cooper mpi and finally got it in for an MOT last week. It failed on a few things but the worse was emissions and its running really rough.

I went to collect it tonight from the garage so I can do a bit more work myself for the MOT but I couldn't drive it very far. It started OK but bogged down as soon as I tried to pull away. It misfired and had no torque. The idle was OK and it would rev from 2500+ OK but awful around 1000-2500rpm. I ended up leaving it at the garage but I don't want to spend a fortune on the garage investigating NIR do I think they can sort it properly. Its more of an MOT station than garage.

I had the head skimmed a few weeks ago and fitted a new copper gasket. I changed the water pump and water temp sensor for new items. The cat is brand new and the exhaust has no leaks.

Could it be valve clearences? Vacuum problem?

I would really appreciate some pointers. I just want to get it home (1.5 miles) so I can get it sorted and back in for a retest.

I found another post via the search with similar symptoms but that wasn't conclusive.

Thanks

Luke

[crazirob]

a few questions

 

Was the engine rebuilt ?

If so who set the engine timing and what is it set to on what cam ?

Has the car been Setup/fueling/Rolling Road's ?

When the head gasket went on what did you se the tappet gaps too ?

[Phil-R]

Please also see crazirob's questions. Although I strongly suspect the vac pipe, there are lots of potential mechanical causes that could be overlooked if just looking for injection related faults.

 

Leaking vacuum pipe - this will cause rough running from 1000 to 2500 RPM, then runs much better over 2500RPM, just as described. To check, completely remove the  vac pipe. Look closely for loose fitting and cracked connectors - sometimes they will fall apart in you're hands, sometimes it's just a subtle crack; There's almost zero chance of the original plastic connectors lasting 15 years.

[LukeH]

Hi

The engine wasn't rebuilt just a head skim, new gasket and service. The gaps were set to 12thou which I hope is correct?

I'm going to get the garage to redo the valve clearences and then perhaps recover it home to start the troubleshooting process.

Thanks for the replies.

Luke

[FlyingScot]

Please also see crazirob's questions. Although I strongly suspect the vac pipe, there are lots of potential mechanical causes that could be overlooked if just looking for injection related faults.
 
Leaking vacuum pipe - this will cause rough running from 1000 to 2500 RPM, then runs much better over 2500RPM, just as described. To check, completely remove the  vac pipe. Look closely for loose fitting and cracked connectors - sometimes they will fall apart in you're hands, sometimes it's just a subtle crack; There's almost zero chance of the original plastic connectors lasting 15 years.

Mate it's an MPi.....no vacuum pipes.

Check the leads have been properly connected up from the ignition pack would be a quick thing to check.
After that you are looking at checking for leaks and recheck the electrical connections.
The IACV on these can stick, plus numerous other niggles. Can you borrow a code reader?
Might be quicker to detect if anything awry.
Always tricky when work has been done to it.....

FS

Edited by FlyingScot, 08 October 2014 - 01:22 PM.

[LukeH]

Please also see crazirob's questions. Although I strongly suspect the vac pipe, there are lots of potential mechanical causes that could be overlooked if just looking for injection related faults.
 
Leaking vacuum pipe - this will cause rough running from 1000 to 2500 RPM, then runs much better over 2500RPM, just as described. To check, completely remove the  vac pipe. Look closely for loose fitting and cracked connectors - sometimes they will fall apart in you're hands, sometimes it's just a subtle crack; There's almost zero chance of the original plastic connectors lasting 15 years.

Mate it's an MPi.....no vacuum pipes.
Check the leads have been properly connected up from the ignition pack would be a quick thing to check.
After that you are looking at checking for leaks and recheck the electrical connections.
The IACV on these can stick, plus numerous other niggles. Can you borrow a code reader?
Might be quicker to detect if anything awry.
Always tricky when work has been done to it.....
FS

Thanks for the pointers. I guess I'll need to start with the basics and work my through the various systems. I just don't want a mechanic doing it at the stage sucking funds that could be spent elsewhere on it.

The priority is getting it home then I'll see if my usual mechanic will lend me his code reader. I just hope it's something simple and not a scrap engine as much as I'd love to do an engine transplant I really can't spend that sort of cash at the mo after 3 years of replacing everything else.

Cheers

[Phil-R]

Mate it's an MPi.....no vacuum pipes.

would help if I read the question properly.

[Fast Ivan]

I would start with the basics - general service, check earths, fresh fuel, valve clearances

access to a code reader is a must really for the injection owner, but if I was to guess at it I would say the TPS would be my suspect

[LukeH]

Well I goit it back from the garage tonight. They have redone the valve clearances which has improved it considerably. Its still lumpy low end and running very rich.

As suggested I will start with the basics and see how it goes although I'm not sure I'll know much without a code reader or gas analyser.

What effect what a bad earth have?

[LukeH]

Here are the results of the emmisions;

Fast Idle - CO=7.58 & HC=2141 & Lambda=0.823

Natural Idle - CO=4.350

Its off the scale and smells if strong unburnt fuel. I will be starting the trouble shooting this weekend.

[Fast Ivan]

Well I goit it back from the garage tonight. They have redone the valve clearances which has improved it considerably. Its still lumpy low end and running very rich.

As suggested I will start with the basics and see how it goes although I'm not sure I'll know much without a code reader or gas analyser.

What effect what a bad earth have?

bad earths can cause all sorts of problems there's a few located around the car, off the top of my head there's one by one of the rear lights in the boot, one under the expansion tank, one on the inner wing and one behind the cd player, these are the main loom earths

[LukeH]

Right everyone I picked up a snap on mt2500 fault reader and I've carried out some tests today. I noted down all of the faults and then cleared them and the following four reappeared. These seem to come up a lot together on Google searches.

05 ambient air temp sensor
13 oil temp sensor circuit
23 oil temp sensor circuit
25 ambient air temp sensor

I ran the engine up to temp and got;

Engine RPM 1003
Throttle valve position sns (v) 0.60
Battery voltage 14.3 v
Stepper motor position 0
Coolant temp 94
Intake air temp 55
Oil temp 91
Throttle valve pos (°) 4.23
Throttle valve position open
Map (kpa) 55.60
O2 sensor 2.4 - 3.4 v
Mixture adaption 80℅
Ambient temp -214
Canister purge valve - open

A few things jump out at me. The throttle position angle and saying open when it was just ticking over and throttle not being pressed. I tried 3 different tps's and they all said the same. (I disconected batt after each swap)

The o2 sensor readings seem high. I thought it should be between 0.1-0.9v? It drops when the engine is off.

The fan did not kick in despite engine temp being 94°. I pulled the sensor and the fan came on. I've got a new 88° thermostat on order and the temp sensor has already been replaced.

I've checked earth points and I cleaned them all. I also checked contunity from ecu plug to tps for each wire.

I've checked for air leaks by spraying carb cleaner on pipes, injectors etc....and the engine note didn't alter.


Any ideas? Where do I start?

Thanks.

Edited by LukeH, 26 October 2014 - 06:11 PM.

[Fast Ivan]

yeah the oil and ambient temp codes can be ignored

 

the stepper motor should not be reading 0, (idle air control valve) this might explain why its idling at 1000 

the tps should be between 0 -1v when closed

lambda, as you say should be fluctuating with much lower values

the fan doesn't come on until 105 degrees and goes off at 96

 

what do the sensors do when you drive or rev the engine?

does the tps voltage rise as you depress the pedal?

what does the map sensor do when you rev the engine?

[LukeH]

what do the sensors do when you drive or rev the engine?

does the tps voltage rise as you depress the pedal?

what does the map sensor do when you rev the engine?

 

A quick test from cold start and I got the following.

 

Engine RPM - 1476 (starts first turn of the key no problem)

TPS (v) - 0.68 and varies if I rev the engine

Steper motor - 75

TPS position - closed even when revving the engine

Map - 35 - 36 varies if I rev engine

TPS position (degree) - rises if I rev

[LukeH]

I decided to swap the IACV for a spare tonight and it seemed to run a lot smoother and throttle response was better but that could be coincidental. I took reading on the snap on again after a few minutes of engine running and at full running temp.

 

After startup (Warm Engine)

 

Engine RPM - 1593

TPS (v) - 0.69

Batt Volt - 14.309

Step Motor - 76

Coolant Temp - 57

Intake Temp - 33

Oil Temp - 52

TPS - 6.07 degrees

TPS - Closed

Map - 37.83

O2 - 2.4-3 v

Mix Adaption - 104%

Ambient Air - -214

Purge Can - Open

 

 

At running temp

 

Engine RPM - 1359

TPS (v) - 0.68

Batt Volt - 14.309

Step Motor - 76

Coolant Temp - 105

Intake Temp - 59

Oil Temp - 91

TPS - 5.81 degrees

TPS - Closed

Map - 40.78

O2 - 2.75

Mix Adaption - 81.40%

Ambient Air - -214

Purge Can - Open

 

 

The revs seem to drop down and then pickup again but don't seem to want to idle below 1000rpm. I guess I could take it for a short drive and see if that makes a difference. The fan kicked in at 105 degrees and it didn't boil over so I'm pleased in that sense but judging by those figures and would say my emissions are still going to be high.

 

What next ? worth changing all the sensors one-by-one and retesting?

 

Luke.