2seater

Thanks. Just done as an exercise for an obsolete engine family to see what could have been😐

Good to know it is happy now. As these cars and systems age, the normal and expected failure modes seem to morph into new ways to test our resolve.

Not a lovely creation but should be better within the original design envelope, maybe sound a touch different?

This is a quick photo of a complete set done in about 2001 in titanium gray. The crossover pipe is somewhat obscured by the manifold on the left. The darker gray is the modern take on the same color and has not been installed or run yet. The dark gray one is heavily reworked in the area of the exhaust outlet to eliminate the turbulence where the exhaust from the front and rear exhaust ports run into each other at the outlet.

No, they generally don't go bad, they are a low grade 400 series stainless steel. For appearances, just have the existing ones ceramic coated. I use satin black for turbo piping, which is pretty much a temperature requirement, or titanium gray for naturally aspirated, but lots of colors are available. If coated inside and out, the heat shields can be eliminated in some areas.

No, it will not fit. The Series II ports are evenly spaced and the LN3/L27 are not. Pretty much why Series II heads won't work on the Series I also, the valves are in a different order, and the deck of the block is nearly 1" shorter.

I would bet on the CPS. I know they aren't supposed to semi-heal and all that, but from personal experience, it can act exactly that way. The other possibility is to check the harness for routing and assure the connection at the ICM is clean, tight and no damaged pins.

Bummer.

Well, full throttle goes to open loop. I don't remember exactly where in the TPS scale, but at a certain point, like 3/4 or so, it goes into fuel enrichment. I am not certain what that all means, but things do change above a certain throttle position, and it is easier to fire a slightly rich mixture vs a lean one.

I don't have a reasoned conjecture at this point but simply a caution to not assume a sensor is operating correctly just because there are no error codes. It is possible for a sensor, such as the MAF, to give incorrect information and remain within parameters so it doesn't trigger a code. Todays control systems are much more powerful and cross check multiple inputs, but our older systems are much more coarse. That said, something like a snapshot of sensor readings where it is acting up may reveal something, or simply pick a sensor to watch to see if it performs as expected, such as a steady increase in MAF reading as acceleration ramps up. From previous experience I would expect a maximum of 125ish on the MAF at the full throttle shift point. Now if the engine stumbles, the MAF will drop, so careful observation as to timing of events is necessary. I only use the MAF as an example. Take a look at O2's, Integrator and Block Learn to get an idea if it is running out of fueling, or perhaps something is triggering the knock sensor which will pull timing.

This is a five or six year old thread regarding the climate control repair, which wanders around a bit trying to understand the inner workings of the HVAC controller, and that is my guess for your problem. With no vacuum to the system, the air direction defaults to the defrost position, just the opposite of what you are reporting. If you are willing to access the controller in the right side dash, standing vertically, connections on bottom, you can run the various air doors manually with a vacuum pump to see if they work. Either the defrost/vent door is stuck or the controller is sending vacuum to the door holding it in the vent position. The FSM assumes the HVAC module in the dash is functional of the indicators change as per your input:

I don't know what the issues are with this unit but an '88 has a one year only motor and pressure hose assembly, so I would at least save those parts.

Ahh, so. I know little about the steps involved but I guess something must come first🤔

Dave, I thought you used the low mile good parts from the '88? If that's the '88, so much the better for me😎 It does measure good, and just had the oil holes chamfered and journals polished. Ronnie, The X is in a similar position, perhaps slightly more clockwise? Are you thinking it is some sort of index mark, maybe before the keyway is cut, which would seem to be a more robust way of alignment.

I looked at the crank I just got back from balancing, an '89 I think, and it has an "X" stamped in the end of the snout. The stamping is distinct but not very deep like Padgett's is. The end of the crank snout has a large chamfer, so it would seem a punch mark would not upset the outer diameter. Padgett's looks pretty deep, is a peculiar shape and may be several separate hits, so maybe???

Have you tried one of the spares to see if slip fit or not?

Did you have symptoms of poor brake performance before this change?? Any salvage yard part will require testing to determine the quality level, so that is an unknown at this point. From the many pumps, switches and accumulators Daves89 and I have tested, the switches rarely fail unless they leak into the electrical connection, the pumps are generally pretty robust as well as long as they get clean fluid. The one item that is the most common failure point is the accumulator, which if left in a defective state, will shorten the life of the pump and possibly the switch due to constant cycling.

Good advice here. From the previous descriptions, it sounds like all parts previously replaced have been new except the ICM?

It sounds like you have addressed my likely culprits, but it pays to double check all the connections and harness for issues. I am curious about the several CPS replacements? They are pretty reliable unless damaged so multiple replacements sounds unusual. Are any codes present? I have not had any issues with the ECM, so hard to say symptoms, but it is the brains behind the engine operation, and sure never hurts to have a known good spare. Fuel, air and spark, just need to narrow the list, easier said than done sometimes🤔

It is difficult to diagnose when it won't stay broken, but from those symptoms, I would bet on the Crank sensor or the ICM under the coils. Did the tachometer on the dash quit at the same time or perhaps just before?

For the asking price, they didn't spend much on the photography, low resolution, aside from the misleading and incorrect description. Maybe the unclear photos are to make it appear like it really isn't there?

The opening in the red/white courtesy light is simply a hole that allows the illumination from the courtesy light bulb to enter the fiber optic cable and shine on the ring around the external key hole. If the door mounted courtesy light doesn't work, the fiber optic cannot function either.

Fuel pressure sounds good, so likely is not the problem. That leaves two items, spark and fuel injector signal. A noid light or something to indicate off the injector connection would be helpful and spark tester(s) to see if the spark goes out. The two are sort of intertwined so determining which quits first may be difficult. Holding the throttle open slightly will bypass the IAC if that is restricted. I am almost to the point of suggesting the ECM as the culprit but unfamiliar with the '91 electronics.

38psi under what conditions? Engine running, engine not running, the details are everything. Bleeding down to 30 that fast is a little excessive, but not horrible. Wet plugs would seem to indicate too much fuel, poor spark or multiple tries to start it with limited results, causing it to go through multiple prime cycles. Hot wire the pump by applying 12volts to the green connector near the brake cylinder to run the pump constantly and see what the results are. Try to start with it hotwired, it won't hurt anything.

I am not certain about the normal fuel pressure for the TPI L27 engine, but the intake and fuel rail pressure I have for a TPI manifold appears to be the same as the '88-'90 LN3, or approximately 3bar or 43.5psi with key on and engine off. I believe later models did use a higher pressure.