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So closing this issue off, I bought new Chinese injectors on ebay that are low impedance injectors that are supposed to match the original Bosch injectors, They came with hoses, fuel injection hose clamps and the rubber doughnuts and o-rings. The injectors were the four spray nozzle type that should atomize better and after 4 hours of messing around installing them, the car is 90% cured. I'm now getting a slight hesitation on the drivers bank but I also hear a huge sucking sound which I expected was the vacuum line to the transmission as this is the area the car caught fire when the cats got hot. A quick shift into reverse confirmed this.
Not really fond of the idea of crawling under the car at the house as all I have is a pair of Harbor Freight jack stands but I'll take it up to the shop soon to inspect the underside and fix the vacuum line.
Generally reports of the quality and matching sprays of Chinese injectors has been spotty at best. Doesn't mean one wont' get a good set, but there are bad reports out there (not specific to any particular maker/injector type though).
I don't think that those are the same injectors as they are painted black, The connectors are a different color, and the hose clamps are not fuel injected rated. Those actually look like used originals whereas mine were 100% new.
So I'm hearing a pretty significant vacuum leak from the V of the engine behind the distributor. As I mentioned the insulation caught fire from the cats and may have damaged the vacuum lines (should read as did but I've not been able to trace it), I know that the reverse lights don't work anymore.
The vacuum modulator does not get vacuum anymore and when i took it for a shake down, It would change gear.
So few questions:
1) Does anyone have a good vacuum diagram for these cars? It has to be stupid good as I'm pretty stupid and visibility is not great. For a 1990 XJ12 NA spec
2) The little cannister which looks like a vacuum canister may have melted in the fire (the one behind the throttle tower), is that available new?
3) Can anyone tell me the size of the vacuum lines? I'd like to order bright colored silicon lines on Amazon
4) In my experience with MB transmissions, no vacuum to the modulator would cause hard shifts but not no shifts. Did I screw something else up in the process of replacing the plugs and injectors?
The vacuum modulator for the transmission gets vacuum from one of the nipples at the rear of the RH intake manifold. No vacuum would result in a very late and harsh 1-2 shift, if it shifts at all.
There should be a vacuum diagram label on the underside of the bonnet although these are not always helpful. Sometimes the parts manuals should the vac hoses pretty well, such as this: https://parts.jaguarlandroverclassic.../brand/jaguar/
The cannister behind the throttle tower sounds like the sending unit for the oil pressure gauge
Jaguar used a variety of vacuum hose diameters. I would think that an assortment 3mm, 4mm, and 5mm would do the trick.
OK the vacuum line to the transmission was cooked so I replaced it which resulted in the car not slamming into gear as it did before but it's still difficult to shift. I'm still getting a giant sucking sound from the rear of the engine behind the distributor. It sounds like it's coming from under the tower but I removed the tower and could not see anything out of the ordinary. What I did notice is that on the drivers side intake, there's a hose that comes out of the back (about 1.5 inches thick) that would collapse when you rev the engine. Also the hose that goes to the back of the distributor just routes to a filter looking thing on the drivers side fender.
I tried to take the car for a shakedown but the tanks are not switching correctly so i'm getting massive vacuum the drivers side tank while the passenger side overflows.
Well, vacuum off the side of the intake is direct high vacuum, so perhaps a replacement hose is needed, BUT, how is the hose to the Vac Advance module on the Distributer metal body? Is it working? Does it hold vacuum? Does it move? The "filter" one you describe just goes to the cap and vents it to air to prevent PVC vapors coming up through the shaft building up and grenading the cap w/ the right hydrocarbon/spark mix. The two other vacuum(s) that should be in the V are the one to the crossover pipe at the back of the engine that provides the MAP signal to the ECU via a LONG pipe, and then of course available vacuum to the crusie control solenoids. A little further out is of course the vacs to the fuel pressure regulators and the crossover vac pipe in the center across the tops of the intakes.
OK thanks. So I need to focus my attention to the vacuum line that goes to the ECU and the one to the cruise control which is not functioning on this car. I've not checked the vacuum advance on the distributor yet. But both the hose to the vacuum advance and the hose to the top of the cap are connected
The vacuum signal is how the ECU determines load and how much fuel to inject, so it's critical there are no vacuum leaks. Similarly, that is also how the transmission shift points are altered. If you have no vacuum to the transmission it's reading that as full throttle and while shift at high RPM and will increase the line pressure inside the trans. Not great for a long life.
Last edited by Jagboi64; Apr 27, 2023 at 09:58 AM.
