Discussion
I've had my car on a rolling road to try to identify the cause of a misfire. I had replaced the usual suspects such as dizzy cap, rotor arm plugs and leads before the run. Readout under load showed that the engine had a lean misfire which points towards a couple of dirty injectors. The cost to remove clean and test will come to about £250. Before I spend that amount of money has anyone tried injector cleaner (Wynns, STP, Halford etc) and did it work?
The work to remove and refit is very straight forward, so you can reduce the labour costs dramatically if you want. I think a clean/service is of the order of £20 per injector. If you *really* want to save costs you could try looking at the plugs and see whether any of them are obviously overheating, indiating that these cylinders are running lean. But cleaning them all is sensible, anyway.
I had a look at the plugs before the rolling road session. They all looked the same with grey ceramic and dry sooty outer body, which as I understand indicates too much use in traffic. This fits because I use my Griff for commuting during the week so it never gets hammered till week end. The Bible (page 102) makes the task of injector removal look a little daunting. I am quite useful with a tool box (built a couple of kit cars and restored a couple of bikes) but V8's and fuel injection is new territory. How do I de-pressurise the system? What are the dodgy bits?
Removing the injectors can be fiddly , but essentially easy.
Of course you have to relieve the pressure in the system, maybe undoing the fuel supply line slightly.
Plenum cover off, remove the four pins that hold down the fuel rail, disconnect the injectors and ease the rail up one side at a time.
The injectors should manouvre out now.
A
Of course you have to relieve the pressure in the system, maybe undoing the fuel supply line slightly.
Plenum cover off, remove the four pins that hold down the fuel rail, disconnect the injectors and ease the rail up one side at a time.
The injectors should manouvre out now.
A
In line with expert advice that I had an injector problem, I fitted a brand new set of injectors (thanks for help Quinny). Didn't make a blind bit of difference so I was peed off even more. Made an appointment with Ian at Middlewhich (5pm Saturday)and left at 9pm with two faults sorted, an oil and filter change, and renewed love of my Griff. Solution was identified by Ian (using a couple of secret tricks of the trade)to a faulty nearside 'Lambada' (as Ian calls them) plus a fault with the HT system to pot 1.
There's some very dodgy diagnosis going on here, then. You can test for a faulty lambda sensor very easily just by monitoring the output voltage when the engine is in closed loop operation. But that's irrelevent under power because the engine runs open loop and ignores the lambada sensors; it seems very unlikely that this was causing your misfire under load. I would be very disappointed if somebody who was diagnosing problems using a rolling road didn't pick up on a simple ignition-induced misfire.
Was it a misfire under load at low rpm or high rpm? just asking because my V8S stays in closed loop to 3500rpm even under full throttle so if it was a low rpm misfire i can well believe a lambada (hehe) being one possible cause. above 3500rpm mine goes out of closed loop, however teh fuel trim that the lucas learns is one value at idle and this is applied across the whole rev range, so if it was weakening off the mixture on the trim at idle because of a faulty lambda then that wouuld make the rest of the rev range weak aswell 
Ian's a top fella-me-lad so I'm dead chuffed it was he who fixed it for you. nice one
Ian's a top fella-me-lad so I'm dead chuffed it was he who fixed it for you. nice one
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