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Discussion Starter #1
1987 HCi, Bosch injected car

Head scratcher driving the car to work this morning.

I started it up, let it go through its warm up cycle as usual. The entire drive to work, the car would not rev past ~3,000 RPM. When the tach would get in that area, the car would struggle as if it weren't either getting spark or fuel. Not sure which it would be.

This past weekend, I changed the plugs and wires, but I was able to drive the car without any issues several times since then.

Last night, I checked the tension on the timing belt (which was spot-on, by the way). I also did a little bit of degreasing and tidying up.

I have to think that while I did that stuff last night that either I knocked something loose, or got degreaser some place it shouldn't go. But I can't imagine what.

The car starts perfectly fine, idles fine, doesn't make any funny noises (that I can hear), and revs just fine until that 3,000 RPM "limit".

Something else that strikes me as odd/interesting is that sitting in neutral, I can rev it past 3k, sometimes quite a bit, before it has the issue. But driving (in any gear), it hits that 3k "limit" like a brick wall.

Any and all thoughts or ideas would be greatly appreciated.
 

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Discussion Starter #3
Thanks. Can you help further on that second point, please?
 

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Discussion Starter #5
I would start by replacing the fuel filter and the air filter.
David Teitelbaum
Air filter was replaced last fall. I have a spare fuel filter that I will install as a matter of due course. It just strikes me as a "I must have done something" situation because I was in the engine bay last night, and now the car is misbehaving.
 

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Yo Mikey - yeah...the old "I was in there and knocked something off" rings a bell, doesnt it? been there, done that as you know.

Hmmm..... Just as a thought.... That engine overspeed module which is mounted in that hard to reach area *could* be an issue. Remember when Rick came over because my car wouldnt start and he reseated that connector and wlla - she fired right up? Now, that likely happened because I didnt mount it back where it was supposed to be so it prolly loosened itself over time.

So, if you can , it might be worth getting at that connector and reseating it and even slightly bending the pins so they make better contact. And, the female end of that connector did look iffy(Atwell confirmed that too) and it wouldnt hurt to replace that or at least clean it really good. Any looseness with that connector and problems like no fuel(which I had happen) could result. Or, if one of the fuel pump connections is shady the car will "think" its got a bad fuel pump and will limit RPMs to 2800 - aka "limp home mode".

Id start with that OSM since its caused me some fits. And, by the way - I do have my original one which you can have. Its not likely that module but you should take the spare anyways. Its a hard to find part these days and they arent cheap!

get back to me and let me know. I will say this: Any issues Ive ever had with that car that are fuel related have always been something I did so thats good. Im sure its something minor ;)
 

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1987 HCi, Bosch injected car
[snip]

I started it up, let it go through its warm up cycle as usual. The entire drive to work, the car would not rev past ~3,000 RPM. When the tach would get in that area, the car would struggle as if it weren't either getting spark or fuel. Not sure which it would be.
[snip].
Maybe the EBPV (?) - if it's stuck, I think it would do the same.
(Exhaust Back Pressure Valve - keeps closed during cold start to speed up catalayst temp - for cleaner cold start emissions).

When I drive home from work, the car is a slug until the temp gets to about 75C. Even if I floor it, it would smoothly, but firmly, hold at about 3K RPM.

Once the EBPV opens, it's good. So a stuck valve (I think) would sound like what you got?

Others here have had actual stuck valve and can confirm better than me.
 

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Discussion Starter #8
The Bosch G-cars have an EBPV?
 

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Those conditions exactly mirror what my (non-Lotus) car did--twice--when the catalytic converter blew off its moorings and the catalyst honeycomb clogged the exhaust. I could rev my car to 7,200 rpm stationary with no seeming issue. Put it in gear, hammer the throttle, and the engine Would. Not. Rev.

This has happened twice to me with aftermarket "High Flow" cats.

However, I also "second" the other issues posted, which from reading prior posts such as clogged fuel filter, gummed up moving parts, and fouled/screwy electrical connectors. All good things to check, and things I feel every Esprit owner (esp. me--I'm the king of Overlooking the Obvious lol) should put on a "semi-regular checklist".
 

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I'm thinking possible vacuum leak.

Take a quick look at all the vacuum lines and see if you injured any old ones while you were in there. Due to heat and age, the vacuum hoses on an Esprit might look nice visually on the outside and yet crumble to the touch. Don't ask me how I know...LOL

Roy
 

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Check you haven't accidently pulled off your Vacuum hose to your distributor, IIRC the advance starts to come in around 2900-3000.
 

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Discussion Starter #13
Okay, got home from work and I have probed around a bit. The car is in the one fuel pump limp mode.

Both pumps have continuity across their posts. One pump (the one with the fat fuel hose from the tank, so I guess primary) has 12v across its posts when the car is running. The other one has NO volts.

For the functional pump, there is 12v between its fuse, and ground. The non-functional pump has NO volts between its fuse and ground. I checked continuity across the fuse, and that is fine, so the fuse is fine.

It is REALLY hot outside, so I'm taking a break right now. If I recall correctly, there is a relay, and the overspeed module to check as well.
 

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Discussion Starter #14
There's a relay for each fuel pump, so I swapped them. No change, there is still no power across the fuse for the one pump.
 

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Discussion Starter #15
According to the wiring diagram, the fuse is fed power from the overspeed module. I'll have the "joy" of getting to that after dinner.
 

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Discussion Starter #16
I took out the overspeed module, and cleaned the connector pins, applied dielectric grease.
Before putting the module back in its cubby, I started the car.

At that point, I had voltage across both fuel pump fuses. However, as soon as I put the overspeed module back in its cubby, I lost power across the same fuse as before.

Not quite sure how I'll resolve this. Open to suggestions, please.
 

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I[snip]
At that point, I had voltage across both fuel pump fuses. However, as soon as I put the overspeed module back in its cubby, I lost power across the same fuse as before.
[snip].
I would not focus (yet) on the overspeed module (as it's more solid state than the fuel pumps).

Are the fuel pumps the original 27 year old pumps? The intermittent behavior of the pump may be due simply to a failing pump. You could try and get the pressure gauges to test the pump pressure, but if they're that old, seems likes living on borrowed time.

My old 76 Scirocco had Bosch CIS and a failing pump displayed intermittent behavior similar to your rev limiting - I had to lie down on pavement and kick the pump (near passenger side) to get it running again.

Due to that experience, I replaced both my 88's Bosch CIS fuel pumps immediately when I bought the 23 year old car - the original pumps were still working when I removed them. I wasn't going to depend on 23 year old fuel pumps for a daily driver.
 

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Discussion Starter #18
My point isn't the overspeed module itself; it is the connectors that join the module to the harness are very flaky.

By just slightly wiggling the connector, or placing the module in such a position that the wiring either has more stress or less stress, I can cause the power across the fuse to either appear or disappear.

I do 100% agree that an older pump is a concern, but based on my consistent reproducibility with the connector/wiring, I am thinking that the issue lies there.

When I had the connector apart, I did my best to clean it, but even so, it doesn't look like it is in great shape. What I am having most trouble with is cleaning & tightening up the female end - the plastic connector fairly buries the terminals, so it is hard to get in there.
 

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Somewhat similar experience with my 1989 Porsche 928S4

At initial start would run fine, etc. but after warming up a bit not so much. Ended up one of the fuel pumps was on its last legs and until it got warmed up (overheated due to on last legs?) it would then stop and the remaining pump wasn't up to task above around similarly 3k RPM...
 

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Discussion Starter #20
I'm going to pick up a set of miniature files today and get the female side cleaned out. It looks really, really manky - visible corrosion, etc.

If that resolves the reproducible "wiggle and power goes out" issue, and the pump continues to run, then all good and I'll eventually replace the connectors with a GM Weatherpack connector.

If that doesn't resolve it, I'll venture on to checking on the fuel pump.
 
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