Time to address the long-standing issue with this car

Technical Area Engine, Transmission, Exhaust etc
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  1. My model of MX-5 is: 1990 NA
  2. I’m based near: Chesterfield
  3. I’m looking for technical help or recommendations on: Car just hates hills

It’s me again.

Had the car 2 years, still haven’t gotten to the bottom of why it sucks at uphill.

For context:

Going up the hill from Chesterfield to Matlock (just before Slack), I’m in 3rd gear going 30mph. Halfway up this hill, it changes to a 50. I drop to 2nd, foot flat to the floor, car does literally sod all :joy:

I can understand that, at 37 years old, she’s not going to have 118bhp anymore. But when a friend’s car that to my knowledge has no power-gain modifications on it except exhaust and intake (which mine also has) can do it now problem, I’m beginning to wonder.

Car seems to perform perfectly fine everywhere else. Low-rev is obviously pointless because the 1.6 engine loves to rev high. And at 4k+ the throttle response is brilliant. However that mid-range (2-4k) doesn’t do anything. On occasion I’ve noticed that if the hill is steep enough, I actually start losing speed and power.

Unsure where to start checking

As a side note, I do have a blow in the manifold that I’m hopefully fixing in the next couple of weeks. My intake is Jackson Racing CAI as those who are regulars here have seen me panicking about (because I’m a moron), Cobalt exhaust. Everything else is stock apart from suspension and some gimmicks.

Timing WAS at 12⁰ ADV when I change my CAS o-ring last year, but I reverted it back to the factory 10⁰. Haven’t really noticed any power changes as a result of that.

Engine has done 126k miles (118-122k at the time I originally noticed the issue).

Am I expecting too much?

2

If I were you I’d consider an aftermarket ecu and a wideband lambda to take full advantage of the mods you have already done.

1 Like
3

Didn’t think an ECU would be necessary but I’ll have a look for sure :slight_smile:

I also don’t have a lambda sensor. I have a deactivated one plugging the hole in my midpipe.

4

Here is a graph I found on skuzzle Facebook. This is for a 1989 shortnose crank engine with no mods. These figures are wheel horsepower. Showing about 5lbft increase throughout 2500 to 4250 rpm. With the intake/exhaust yours would be better still.

IMG_0809
IMG_08091389×1999 495 KB

5

Have you got a different manifold? If you have a long header manifold, the exhaust scavenging will be more effective in high rpm but less effective for low rpm. Just something to consider.

6

Have you still got a catalytic converter fitted? I Once had one break up and when going uphill or spririted driving it would Lodge sideways in the exhaust blocking it up and drastically reducing power.

Or maybe you just have clutch slippage?

7

I have the stock manifold still, but it has a blow. Replacing it in a couple weeks with a Cobalt 4-2-1.

I’ll have the full Cobalt set then

8

I never had a cat in the car.

Got a new Genuine Clutch and gearbox in 2024