MR2 roadster pre cat issue - what should compression be?

[vee5]

Currently looking at a 2004 face lifted MR2 with 28k on the clock. I've read a lot about the potential for lunching the engine if the pre cats breakup, so before buying the car I'm going to run a compression test to see if the engine has already suffered any damage - does anyone know what values I should be looking for on the test? Thanks!

[Marf]

1zz engine?

Should be above 145psi

http://madstyle1972.com/Repair/14/200f0c04/i740001...

[vee5]

Thanks, I "think" its a 1zz engine series - can someone confirm that for a 2004 facelift MR2?

[Crazysteve]

Hi, i think face lift is the 2zz.
They changed the piston and oil rings design post 2003?

http://www.mr2roc.org/phpBB3/viewtopic.php?f=11&am...

We have a 2001 oil burner, removed the precats last year.
Still has good compression but 1 ltr of oil to 250 miles not so good.
Planning on taking the engine out next week, to check see if it is oval bore syndrome, i have seen posts where it has been caught early a hone and new rings may sort the problem.

[Red Devil]

vee5 said:

Thanks, I "think" its a 1zz engine series - can someone confirm that for a 2004 facelift MR2?

Crazysteve said:

Hi, i think face lift is the 2zz.

No. Toyota only ever fitted the 1ZZ-FE to the Mk3. The 190bhp 2ZZ-GE is used in the Celica T-Sport/GT and the Lotus Elise/Exige Series 2. It is a perfectly viable swap into an MR2 Mk3. I know several people who have done it. The result is the car Toyota should have made from the start. If that isn't enough grunt for you, supercharge it (as in the Exige S) and you will have 220bhp on tap.

[liner33]

Its more important that all the readings are within 10% of each other , a compression test by itself tells you very little

[vee5]

I can appreciate why all the readings should be similar but i disagree that a compression test on its own will tell me very little - surely its the best way of determining whether the engine has already suffered damage eg from ingesting pre cat material? If the test shows 180psi I'll be hapy to buy the car, if it shows 145 I'll be walking away.

[Red Devil]

A compression test is a minimum. Get leakdown and sniffer tests done as well.

[liner33]

Compression test on its own wont tell you the engine has ingested anything all it will tell you is that the compression is low

Recent figure from my Evo

Cyl 4 = 160psi
Cyl 3 = 170 psi
Cyl 2 = 165psi
Cyl 1 = 168psi



Not too bad within 10% so not a concern

But leakdown results

Cyl 4 = 16%
Cyl 3 = 2%
Cyl 2 = 2%
Cyl 1 = 8%

Bit more worrying

Next borescope



Finally strip down




Result one wrecked motor , but based on compression test it was fine , so as I said it doesnt tell you very much at all

[vee5]

So what would "good" compression figures be for your evo then?

[liner33]

150psi +