Got my car mapped! Bad News though!

Vipernet

Vipernet

Vipernet

Soldato
Joined
18 Oct 2002
Posts
2,883
Location
2 doors down from Subo
Well after a lengthy rebuild process and a very boring running in period of approximately 800 miles the time came for my mr2 turbo to get mapped!

I took it across to Ayr to get mapped, fitted the emanage ecu, wideband and det cans and set off with the mapper in passenger seat who gave me strict instructions to immediately back off if he told me to, and there was to be no sideways action :p

Anyway, first run in 3rd gear and my face lit up. The boost came on hard and the car shot off, however this was shortly followed with an abrupt shout to lift off from the mapper :mad:

Turns out that as soon as I'm hitting 1 bar of boost my 540cc injectors are maxxing out at 100% duty and I'm starting to get detonation :(

The turbo and engine is quite capable of handling approx 1.5bar of boost and I'd like to utlise this fact. So off to ebay I went and ended up buying a set of Sard 850cc injectors :p Gonna be a pain to fit but I'm changing to an external wastegate and screamer pipe at the same time which should be fun!

On the plus side I must surely be running in excess of 350bhp at 1bar of boost if I'm maxxing out 540cc injectors!
 
Exhaust = straight pipe from the turbo, exiting via the nearest body panel.

With the screamer pipe (love them! ;)) exiting parallel to it. Moby Dick stylee.

*n
 
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Can your pump provide enough fuel for your new injectors?

Quick calculation :

Needed fuel pressure = ( PR^2 x idle pressure) + boost

Pressure Ratio (PR) = 14.7 + boost / 14.7

Example:
6psi = 1.408 Pressure Ratio
1.4082^2 = 1.98
OEM Idle pressure = 36 (Larger pumps may mean more idle pressure)
(1.98 x 36) + 6 = 77.38psi
At 6psi you want to be able to supply 87psi of fuel (10psi more than needed to be safe).

To determine the amount of fuel you can supply with your AFPR or FMU follow this calculation:

Fuel pressure @ rail = Rise x boost + idle pressure

Examples: 10 x 6 + 36 = 96psi
8 x 6 + 36 = 84psi (good match)

Might want to figure it out!
 
penski said:
Exhaust = straight pipe from the turbo, exiting via the nearest body panel.

With the screamer pipe (love them! ;)) exiting parallel to it. Moby Dick stylee.

*n
Click to expand...

Exactly! :D I'm thinking about a single screamer pipe exiting via one of the side vents for maximum flamge and effect!
 
Firestar_3x said:
Can your pump provide enough fuel for your new injectors?

Quick calculation :

Needed fuel pressure = ( PR^2 x idle pressure) + boost

Pressure Ratio (PR) = 14.7 + boost / 14.7

Example:
6psi = 1.408 Pressure Ratio
1.4082^2 = 1.98
OEM Idle pressure = 36 (Larger pumps may mean more idle pressure)
(1.98 x 36) + 6 = 77.38psi
At 6psi you want to be able to supply 87psi of fuel (10psi more than needed to be safe).

To determine the amount of fuel you can supply with your AFPR or FMU follow this calculation:

Fuel pressure @ rail = Rise x boost + idle pressure

Examples: 10 x 6 + 36 = 96psi
8 x 6 + 36 = 84psi (good match)

Might want to figure it out!
Click to expand...

Yeh. Std pump won't do. Replacing the in-tank one with a walbro one which is apparently good for 500bhp.
 
Hardly bad news, just means it making even more power. ;)

At least the engine didnt blow up


OEM reguator on the MR2 will be a simple vacuum reference 1:1 rate. So 1 bar of boost will only be 60psi (assuming a 45psi 'static' fuel pressure).
Walbro is needed, go for the HP version for boosted engines as there flow much better at higher pressures.
 
Dont know if its the same for the MR2 but on the 200 Sard injectors need the injector collars to make them fit. They can be bought from places like Greenline, just a pain in the backside if you dont realise and have to wait another few weeks.

On a side note one of the guys that had a TD06 20g (IIRC you have the TDO6) fitted to a 200 said the car had the ability to scare him it was getting that fast. Should be loads of fun :D
 
Surprised you didn't upgrade the fuel pump first, the injectors will probably be fine if you fix that, standard injectors are usualy ok for 1bar.

It's an utter, utter ball ache to change the pump though. You have to remove all the plastic panels under the car, unbolt the coolant hoses, take off the tunnel trim inside the car and disconnect the pump and sender, disconnect all the fuel lines and filler pipe at the front of the engine bay, then you are ready to unbolts the tank and then manouver it out (gynacological skills handy!). Hope you haven't filled the tank recently!

Whilst the tank is removed have a very close look at the brass heater pipes that run above the tank, the brackets often snap off towards the rear and which causes a coolant leak. Any sign of cracking would warrant replacement or fixing with silver brazing (aka silver soldering). If they go sometime afterwards, you will have to drop the tank again.

BTW, going for monster injectors is a bad idea unless you really need them, chances are that idle quality will be poor with 850cc injectors. I fitted the uprated Walbro pump (was quite a bit cheaper than the Toyota part) but I do find the noise it makes quite intrusive, and it didn't fit into the OEM pump bracket very well at all.
 
Dogbreath said:
I fitted the uprated Walbro pump (was quite a bit cheaper than the Toyota part) but I do find the noise it makes quite intrusive, and it didn't fit into the OEM pump bracket very well at all.
Click to expand...

Yep mine has always made a high pitched whining noise
 
Dogbreath said:
the injectors will probably be fine if you fix that, standard injectors are usualy ok for 1bar.
Click to expand...

But surely with the bigger tubby, he'll be needing more fuel for any given amount of boost, because there is that much more air being forced into the engine compared to 1 bar on the standard turbo?

When I had my car mapped after having the porting done my IDCs jumped by a fair bit simply because of the extra airflow, I didn't touch the boost.
 
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DreXeL said:
But surely with the bigger tubby, he'll be needing more fuel for any given amount of boost, because there is that much more air being forced into the engine compared to 1 bar on the standard turbo?
Click to expand...

All depends on inlet temperatures, if the inlet temperatures are the same the amount of air being consumed will also be the same irrespective of turbo size. The whole point of a larger turbo is higher efficiency at the pressure and airflow you require, i.e. less heating of the air. However, unless there is a significant difference in temperatures then the amount of air being used by the engine will be fairly simmilar in either case.

Another point is that if the injectors are starting to max out near ***, then a simple increase in fuel pressure may cover the difference using stock injectors
 
Tbh I didnt think I'd be pushing this much power and the rev2s run a higer pressure fuel system than the rev3s so I thought that would cover it.

I did some research on the 850cc sard injectors I've bought (with collars I might add) and spoke to a few people who have them on their mr2s with no idling problems. The consensus is that idling problems with mr2s only occur once 1000cc injectors or larger are fitted. I'm gonna order up a walbro replacement pump and if I can afford it a wolfkatz fuel rail.

As for the turbo and power, yes it's a td06 20g and yes the power can get scary. In a straight line the power is fine to deal with (forget driving in the wet) the only time the car scares me is when I'm thrashing it down backroads. You have to be uber careful when applying the throttle because of the turbo lag, I've seen myself plant the throttle half way round the corner only for the turbo to kick and cause me to exit the corner totally sideways :p The speeds you can get up to on little country roads are scary compared to the speed I take them in the mx5. I've already had my father tell me he won't go anywhere near my car again after I took him for a spin :p
 
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