Whats causing my missing cylinder?
Discussion
I've got a blowing exhaust gasket on my 400, so I've pulled the manifold off and plan to do the usual bank of modifications before refitting (notch lower holes etc...
The manifold itself...
Is in decent condition. I had a good look over it for signs of cracks etc. No real problems to note. The leaking gasket was fairly evident...
...by its black soot. I think it was this point where I noticed the biggest worry I have found yet. Soot, or rather the lack of it...
This is cylinder 5 (3rd from front) on the O/S manifold. Its not a trick of the light, that's a total lack of soot in there. The inside of the tube looks brand new. Ruh Roh. Surely the corresponding port on the head is...
...oh rollocks. Clean as a whistle. well, some mild soot but nothing like the others. Right....
I've either lost a spark, which seams unlikely as its never sounded like that, or I've dropped an injector... Thoughts? Its the only port that is as clean as this. I'm thinking it may be more likely to be a spark issue, and the cleanliness is from fuel wash?
The manifold itself...
Is in decent condition. I had a good look over it for signs of cracks etc. No real problems to note. The leaking gasket was fairly evident...
...by its black soot. I think it was this point where I noticed the biggest worry I have found yet. Soot, or rather the lack of it...
This is cylinder 5 (3rd from front) on the O/S manifold. Its not a trick of the light, that's a total lack of soot in there. The inside of the tube looks brand new. Ruh Roh. Surely the corresponding port on the head is...
...oh rollocks. Clean as a whistle. well, some mild soot but nothing like the others. Right....
I've either lost a spark, which seams unlikely as its never sounded like that, or I've dropped an injector... Thoughts? Its the only port that is as clean as this. I'm thinking it may be more likely to be a spark issue, and the cleanliness is from fuel wash?
Step 1: Delete the dreadful failure prone spark plug extenders altogether
Step 2: Make up a set of MSD Super Conductor HT leads
Step 3: Fit MSD Pro-Heat Guard Sleeve over the plug ends of your new MSD HT leads using a good 6" length so the part of lead close to the exhaust manifold is protected too
Step 4: Cover the Pro-Heat Guard protected plug ends with DEI Titanium Protect-A-Boots
Step 5: Ditch the totally inappropriate B7ECS spark plugs specified by TVR and replace them with the far more suitable BPR6ES or better still BPR6EIX iridium plugs
Step 6: Drive & feel the difference
http://www.pistonheads.com/gassing/topic.asp?t=125...
http://www.pistonheads.com/gassing/topic.asp?h=1&a...
Step 2: Make up a set of MSD Super Conductor HT leads
Step 3: Fit MSD Pro-Heat Guard Sleeve over the plug ends of your new MSD HT leads using a good 6" length so the part of lead close to the exhaust manifold is protected too
Step 4: Cover the Pro-Heat Guard protected plug ends with DEI Titanium Protect-A-Boots
Step 5: Ditch the totally inappropriate B7ECS spark plugs specified by TVR and replace them with the far more suitable BPR6ES or better still BPR6EIX iridium plugs
Step 6: Drive & feel the difference
http://www.pistonheads.com/gassing/topic.asp?t=125...
http://www.pistonheads.com/gassing/topic.asp?h=1&a...
Obviously check for a spark 1st thing as it is the easiest test to do
Then start looking at the injectors, with the ignition off disconnect the wiring harness plug from the ecu, diassemble the plug to ascertain the pin numbering as image below shows
Turn the ignition off and disconnect the ECU connector. Check the right bank of injectors by measuring resistance between terminals 2 and 11 (Injectors 2-4-6-8). Check the left bank of injectors by measuring resistance between terminals 2 and 13 (Injectors 1-3-5-7). In both cases, an Ohmmeter reading of 4-4.5 Ohms is expected. If the reading is 5-6 Ohms, suspect one bad fuel injector. A reading of 8-9 Ohms could indicate two bad injectors, and a reading of 16-17 Ohms could indicate three bad injectors. In any case, if the overall circuit resistance isn't 4-4.5 Ohms, proceed to checking for wiring faults or for open-circuit injectors.
You can also use the screwdriver stethoscope method to listen for the injector firing (best done with the engine off so you can hear it) use a couple of mini lucar (spade) connectors with a suitable length of wire to the injector and connect momentarily to 12v power source & earth, you should be able to hear the injector solenoid click, this only proves that the solenoid in the injector is firing, the injector may still be blocked etc.
Also if you have rovergauge you can check out the lambda fuel trims which would also indicate if there is an issue on the relevant bank, you can also use rovergauge to run the fuel pump continuously without the engne running allowing you th run the injector test and check for fuel delivery.
Fresh clean plugs (6's as suggested by COG) and repeat the test, pull the plug and check for fuel smell to prove that the injector is actually delivering fuel.
Best of luck
Then start looking at the injectors, with the ignition off disconnect the wiring harness plug from the ecu, diassemble the plug to ascertain the pin numbering as image below shows
Turn the ignition off and disconnect the ECU connector. Check the right bank of injectors by measuring resistance between terminals 2 and 11 (Injectors 2-4-6-8). Check the left bank of injectors by measuring resistance between terminals 2 and 13 (Injectors 1-3-5-7). In both cases, an Ohmmeter reading of 4-4.5 Ohms is expected. If the reading is 5-6 Ohms, suspect one bad fuel injector. A reading of 8-9 Ohms could indicate two bad injectors, and a reading of 16-17 Ohms could indicate three bad injectors. In any case, if the overall circuit resistance isn't 4-4.5 Ohms, proceed to checking for wiring faults or for open-circuit injectors.
You can also use the screwdriver stethoscope method to listen for the injector firing (best done with the engine off so you can hear it) use a couple of mini lucar (spade) connectors with a suitable length of wire to the injector and connect momentarily to 12v power source & earth, you should be able to hear the injector solenoid click, this only proves that the solenoid in the injector is firing, the injector may still be blocked etc.
Also if you have rovergauge you can check out the lambda fuel trims which would also indicate if there is an issue on the relevant bank, you can also use rovergauge to run the fuel pump continuously without the engne running allowing you th run the injector test and check for fuel delivery.
Fresh clean plugs (6's as suggested by COG) and repeat the test, pull the plug and check for fuel smell to prove that the injector is actually delivering fuel.
Best of luck
You can easily check if you are getting ignition in that cylinder. Start the car, let it warm up just a little (20 seconds), then test the temperatures of the exhaust manifolds close to the head.
The non-firing one will be 100-200 degrees lower.
You either need:
http://www.ebay.co.uk/itm/HIGH-QUALITY-Digital-Inf...
Or:
http://www.ebay.co.uk/itm/Sealey-Cable-Ties-Assort...
The latter because the tip will melt on a working manifold, but not initially on a non-working one until heat soak sets in.
The non-firing one will be 100-200 degrees lower.
You either need:
http://www.ebay.co.uk/itm/HIGH-QUALITY-Digital-Inf...
Or:
http://www.ebay.co.uk/itm/Sealey-Cable-Ties-Assort...
The latter because the tip will melt on a working manifold, but not initially on a non-working one until heat soak sets in.
These manifolds are renowned for leaks where the four pipes go into one. It's a fatigue failure that becomes more likely when the manifolds are removed or refitted due to stress twisting.
The common test is worth doing, it sounds a little mad but the test is to plug the lambda socket and fill the manifold with water. This won't harm anything water is a normal constituent of exhaust gas. Leave them for a few hours and then check for wetness below the four into one connection. If there is wetness then you are on borrowed time, it only gets worse in use. It can be repaired by cutting an access hole in the cone and welding a new piece in the middle of the four pipes. Position the access hole so that the welding is not visible when the manifold is in position.
The common test is worth doing, it sounds a little mad but the test is to plug the lambda socket and fill the manifold with water. This won't harm anything water is a normal constituent of exhaust gas. Leave them for a few hours and then check for wetness below the four into one connection. If there is wetness then you are on borrowed time, it only gets worse in use. It can be repaired by cutting an access hole in the cone and welding a new piece in the middle of the four pipes. Position the access hole so that the welding is not visible when the manifold is in position.
overdriveeng said:
I've got a blowing exhaust gasket on my 400, so I've pulled the manifold off and plan to do the usual bank of modifications before refitting (notch lower holes etc..
Can you tell me what these mods are, anything to make the job easier?I've got the manifolds off for the same reason
Alan461 said:
overdriveeng said:
I've got a blowing exhaust gasket on my 400, so I've pulled the manifold off and plan to do the usual bank of modifications before refitting (notch lower holes etc..
Can you tell me what these mods are, anything to make the job easier?I've got the manifolds off for the same reason
igiveup said:
Alan461 said:
overdriveeng said:
I've got a blowing exhaust gasket on my 400, so I've pulled the manifold off and plan to do the usual bank of modifications before refitting (notch lower holes etc..
Can you tell me what these mods are, anything to make the job easier?I've got the manifolds off for the same reason
Barkychoc said:
Get the rocker cover off, disconnect the coil, spin it over on the starter and check you have some cam lobes pushing the valves up and down.
This is well Worth a try, I had a missfire problem on an RV8 powered car years ago and the exhaust lobe on one cylinder had worn almost completely round. I found it by taking the rockers off and running the car, a bit messy with some oil splashing about but not much and diagnosed a fault I had been chasing for a year.Bit of a slow burner this as I have other projects.
Compression test has ruled out a HG failure. All pistons have matching compression.
New studs bought, manifold to be notched... I am also doing a lot to renew the coolant but once done the inlet will be getting removed for a cam inspection.
Oh, and I went for the better plugs too!
Compression test has ruled out a HG failure. All pistons have matching compression.
New studs bought, manifold to be notched... I am also doing a lot to renew the coolant but once done the inlet will be getting removed for a cam inspection.
Oh, and I went for the better plugs too!
gruffalo said:
Barkychoc said:
Get the rocker cover off, disconnect the coil, spin it over on the starter and check you have some cam lobes pushing the valves up and down.
This is well Worth a try, I had a missfire problem on an RV8 powered car years ago and the exhaust lobe on one cylinder had worn almost completely round. I found it by taking the rockers off and running the car, a bit messy with some oil splashing about but not much and diagnosed a fault I had been chasing for a year.
Great bit of knowledge to learn that is,, I'll never forget that snippet
Bob on
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