Porsche 928 1988 Workshop Manual – OEM Factory Specs

Description

I’ve seen guys crack a 928 block because they used a generic torque spec from a forum. Don’t be that guy. This Porsche 928 1988 Workshop Manual is the only document you should trust when you have the head off that V8. It’s 307 pages of factory procedure, written for the Porsche dealer network. Not a reprint. Not a third-party scan. This is the original OEM document from Dr. Ing. h.c. F. Porsche AG, printed in Germany in 1988. If you’re working on a 928, you need this on your bench.

Repair Groups: What This Manual Covers

Page 3 lists the Repair Groups: Engine, Transmission, Chassis, Body, Heating/Ventilation/Air Conditioner, Electrics, and Maintenance/Selfdiagnosis. Each group has its own numbered sections. For example, the engine group covers cylinder head and valve drive (group 15), lubrication (17), cooling (19), fuel supply (20), and injection (24). This isn’t a summary. These are the actual chapter headings from the factory manual. You get the same layout the Porsche dealers used. No guesswork about where to look.

Fuel Supply Diagnostics – Without the Guesswork

Fuel system work on a 928 can be a pain because of the multiple injection variants. Page 4 shows the table of contents for volume I-A’s fuel supply section. It covers replacing the fuel filter, removing/installing the fuel pump, checking delivery rates for CIS, AFC, and LH-Jetronic (beginning with 1984 models). It also includes hose diagrams, check valve arrangements, and even the activated charcoal cannister for later models. If you’re chasing a no-start or a lean condition, this section gives you the factory test sequence. No forum speculation.

Does This Manual Cover the LH-Jetronic System?

Yes. The table of contents explicitly lists “Checking fuel pump delivery – LH-Jetronic, beginning with 1984 models.” That means the 1988 928 S4 with LH-Jetronic is covered. The manual also includes specifications for idle speed and CO adjustment for USA and Japan models through 1983, and separate procedures for 1983 models. You get the exact pages for pressure regulator removal, intake air sensor, cold start valve, auxiliary air regulator, temperature sensor II, pressure damper, and fuel injectors. This is the complete injection guide for your year.

7 Major Systems Documented

The manual is divided into seven Repair Groups, each with multiple sub-sections. Here’s the breakdown:

• Engine (groups 10-28): Crankcase, crankshaft/pistons, cylinder head/valve drive, lubrication, cooling, fuel supply, fuel injection, exhaust/emissions, starter/power supply/cruise, ignition.
• Transmission (groups 30-39): Clutch, torque converter, manual trans controls/case/gears, automatic trans controls/case/valve body, differential/transaxle.
• Chassis (groups 40-48): Front/rear suspension, wheels/tires/alignment, ABS, brakes mechanical/hydraulic, steering.
• Body (groups 50-74): Front/center/rear sections, doors, hardtop, bumpers, glass, window control, exterior/interior equipment, seats.
• Heating/Ventilation/Air Conditioning (groups 80-87): Heater, ventilation, A/C.
• Electrics (groups 90-97): Instruments, fuel gauge/alarm, radio, wipers/washers, exterior/interior lights, wiring.
• Maintenance/Selfdiagnosis: Group 0 includes general technical data; group 1 covers self-diagnosis procedures.

Every system has procedures with tool lists and safety warnings. The wire diagrams alone are worth the price for anyone tracing an electrical gremlin in a 928.

Get the Factory Sequence for Cylinder Head Work

Group 15 is the cylinder head and valve drive. If you’ve done head gaskets on a 928, you know the torque sequence is specific and the bolts are one-time use. This manual gives you the factory bolt tightening procedure in order. It also lists the valve clearance adjustment specs. Don’t rely on a generic Chilton book for this. The OEM manual also includes the correct sealant types and part numbers. Stick to the factory sequence and you’ll avoid warping the head.

For related manuals, check out the Porsche 928 Workshop Manual for older model years, and the Porsche 928 Workshop Manual – Section: Repair Groups if you need a quick reference to the group structure. If you’re working on a different Porsche, the Porsche 911 Carrera 4 & Carrera 2 1995 Workshop Manual Vol 2 Transmission might be useful.

External resources: The Automotive Industry Overview provides context on why OEM manuals matter, and Manual Transmission covers general theory if you need background.

FAQ

Does this manual cover the 928 S4?

Yes. The 1988 model year includes the 928 S4 with the 5.0L V8. The manual covers all variants sold in North America, including the LH-Jetronic fuel injection system that the S4 uses. It also includes the updated electrical system and ABS. The table of contents specifically lists procedures for models beginning with 1984, so the S4 is fully included. You’ll find the correct timing belt replacement procedure, valve adjustment specs, and transmission service data.

What about torque specs for the cylinder head?

Factory torque values are included. The manual provides the sequence and final torque in Nm. Convert to ft-lb as needed.

Is this a reprint or a digital copy?

This is an original OEM PDF scan of the factory workshop manual, printed in Germany in 1988. It is not a third-party reproduction. The PDF contains all 307 pages, including the original cover and page numbering.

How many pages does it have?

307 pages.

Don’t waste time hunting for specs on forums or using aftermarket manuals that skip steps. Get the real thing. Access the Factory Manual now and keep your 928 running the way Porsche intended.