SP engine problems

[Hammer]

In addition...now the whole car doesn't feel responsive.

There seem to be a lag when accelarating. Not sure if it's because of the hot conditions we've had lately or there is really something there.

The symptom I'm feeling is of lag.... I accelarate, but it seems to bog down and slow to accelarate.

Am I just being paranoid, or do you think they've wound back the tuning of my car in order to lower it's power?

[Garry]

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[Garry]

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[Garry]

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[Garry]

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[Garry]

I think you might find that Mazda have wound back the boost a little on their replacement turbos. The original one made about 7PSI but the one Mazda replaced it with under warranty was struggling to get to 6.5PSI. The one I just fitted direct from Garrett only makes 6PSI because it doesn't have any spacers on the wastegate actuator bracket like the Mazda one did. That will be fixed when I install my EBC

[Boags]

Looks like the forum server went apeshit at about 8.30 this morning...?

[Sean]

In addition...now the whole car doesn't feel responsive.

There seem to be a lag when accelarating. Not sure if it's because of the hot conditions we've had lately or there is really something there.

The symptom I'm feeling is of lag.... I accelarate, but it seems to bog down and slow to accelarate.

Am I just being paranoid, or do you think they've wound back the tuning of my car in order to lower it's power?

I'd also check your cooler piping to ensure that all teh joins are connected properly and not leaking boost.

With teh current roller bearing turbos (and the low boost in an SP) it's possible to still produce max boost pressure with a leak, it's just slow to come on and will feel sluggish.

[MX5-SP]

The cause they provided me was, oil soak through the combustion chamber covering the air/fuel sensor. Thus given the wrong mix reading. This in turn caused the fuel to lean out and increased the heat to the point it soften the conrod for it to bend.

Soft conrod, eh? Better watch out for flying people that might dump on you when driving with the roof down too.

[AJ]

The cause they provided me was, oil soak through the combustion chamber covering the air/fuel sensor. Thus given the wrong mix reading. This in turn caused the fuel to lean out and increased the heat to the point it soften the conrod for it to bend.

Soft conrod, eh? Better watch out for flying people that might dump on you when driving with the roof down too.

aaaaaah, so bits fly off SP's too.............as well as being soft rods

[MX5-SP]

aaaaaah, so bits fly off SP's too.............as well as being soft rods

(Ah...AJ....I just knew you were lurking out there somewhere).

Yes, it seems there is some sort of fault with the SP according to this one report.

What's your opinion?

[AJ]

my opinion.........some dropkick has come up with a VERY lame excuse to try & knock back a legitimate warranty claim, rods break, not bend.....for chrissakes, the aluminium head would be a puddle on the frigging ground before a cast iron rod heated up sufficiently to warp.......soft rod be buggered.......is someone saying they took the standard rods out & replaced them with licorice whips when they bolted the turbo on????...................like most fairytales i see on here, just another crock of sh*t!!


i can't believe that a bunch of supposedly intelligent ppl can get sucked into believing crap like this.............i'm just a dumb truckie.........i don't have 6 uni degrees or anything, but i'm certainly not gullible

[Garry]

rods break, not bend

Actually AJ, they bend and then they get weeker and they then usually break. Daniel from Mania showed us a bent rod at their open day that hadn't broken. He also said that he has seen bent rods in MX5's not fitted with turbos. So you could say that licorice rods are an MX5 issue, not just an SP thing.

The problem, if there is one, applies to any late model boosted MX5 engine with the high compression engine, not specifically the SP. The rods are cast not forged, so they are not as strong as a forged rod. Too much boost and/or to many revs = bent and or broken rods. Running the engine while it's pinging badly will also contribute. The SE runs a lower compression ratio and lower rev limit, probably for this reason.

Interesting that Flyin Miata, probably the most respected turbo kit supplier for MX5's in the US, recommend a max boost pressure of 10PSI for their turbo kits for late model MX5's with high compression engines and stock internals. Assuming that AUS delivered cars have the same compression ratios as US cars then the SP should have been very safe with it's stock 7ish PSI.

[AJ]

sorry garry, just to qualify, i was addressing the ridiculous claim that a heat build up actually softens the con rod, causing it to bend.....THAT is what i called a crock.

yep, overboost/overrev/massive abuse or stuffing around with fuel mapping without knowing what you're doing & causing pinging high up in the revs will bend & break a cast iron conrod, but in my experience, they generally don't bend very far before they break, such is the nature of cast metals.

what i will also say is, IF an engine like the SP's is left at manufacturers specs, or any other 1.6/1.8 for that matter & not treated like it's absolutely hated every time it goes out, i fail to see how it could bend a conrod ever, but, go beyond what is recommended by those who build the car, & this includes Alan Horsely & the SP, & you're asking for trouble.......if flyin'miata say that 10 psi is what their turbo engines should be run at & Alan Horsley says the SP should run at 7 psi & Mazda say that the engine should be rev limited to 7250, there's usually a damned good reason why

[MX5-SP]

AJ...I understood what you were on about. The original comment (read: excuse) was the conrod bent due to excessive heat build up. AJ is correct in that the rest of the engine would be just a puddle by that stage...the inference being the conrods would not bend first.

The same logic has been applied to the Twin Towers (WTC 1 & WTC 2) and WTC 7 in NYC on 9/11...but that's a different subject...