I have a 1989 740GL (built 12/88), non-EGR, that is 1000mi from where I am, so I cannot go out to the garage and take-a-look, but before I do go to where it is I'm trying to identify just which Jetronic it has installed on it.

According to some charts in the 700/900 FAQs, after manufacture date 7/88 it SHOULD have the Jetronic 2.4LH, but I do not remember seeing a diagnostic block behind the left front strut on the wheel house which the 2.4 should have (but not the 2.2).

I see that the LH2.4 should also have only 2 wires to the Idle Air Control Valve (vs 3 for the LH2.2), and that the LH2.4 has a start fuel injector, whereas on the LH2.2 no start injector is shown on the wiring diagram.

I cannot count the wires on the IAC Valve, but I don't remember seeing a 5th fuel injector on the intake manifold. WHERE would it be located if I have one? Do NONE of the LH2.2 cars and ALL LH2.4 cars have the 5th start injector?

The LH2.4 appears to have a separate Ignition Engine ECU with at least 23 marked pins on it in addition to the main ECU in the right kick-panel that has 35 market pins on it according to the Mitchells wiring diagrams for the '89 model (yet the Volvo company diagrams for the '89 LH-Jetronic 2.4, B230F do not show this). If this is correct, and there is a separate, large Ignition ECU, where would the Ignition ECU be located on the car? Mitchell shows a 3-wire "Impulse Sensor" controlling the Ignition ECU that isn't referenced in the factory Volvo diagrams.

The Volvo company diagram for the 1989 LH-Jetronic 2.4, B230F shows NO such Ignition ECU, BTW. I got that diagram at http://www.volvowiringdiagrams.com/volvo/740%20Wiring%20Diagrams/1989%20Volvo%20740%20Wiring%20Diagrams.pdf

Bottom line, I am obviously confused as hell, and not being where I can see and get my hands on my car is not helping.

I want to get ready to diagnose a hard hot-start problem the car developed (you have to depress the throttle and crank 2 or 3 seconds to get it to start), and also it now stumbles when shifted into Drive, or back into Park/Neutral, though it still runs and drives very smoothly and normally otherwise. It would help if I can "school" myself before my next trip out to where the car is located.

My personal feeling is that I have a problem w/ the ECU Temp sensor (hot start problem), and/or possibly the Idle Air Control Valve (since the car stumbles when engine load changes with transmission gear selection).

I have a great Bentley Bosch Fuel Injection Book, but it's non-specific as to Volvos, but is there any part of the Green Book, or other Volvo manual online I can download, or view online that discusses the LH2.2 and LH2.4 as installed on the 700 Series I can access? I have only a Haynes, which is pretty useless.

Is it possible despite my 12/88 build date I COULD have a LH2.2 rather than a LH2.4, and what are the BEST obvious ways to ID which system I have? I suppose the label on the ECU would say if I remove it from the kick-panel when I visit the car (presumably 0 280 000-554 for the LH2.2 and 0 280 000-556 for the LH2.4)? The fact the Volvo wiring diagrams list a LH2.2 system in the '89 diagrams means SOME left the factory this way, but possibly not for the US Markets.

Sorry for the rambling nature of my posting-

Bob