Dynoed graph questions

[martinws]

I put my 90 on a dyno the other day just to see what AFRs were doing and because it didnt cost me anything!

Does this seem too rich?

Car seems to boost to 22psi no bother but not sure what these cars normally run at? Its a chipped ABY.

[prj]

Yeah, that's too rich, which would also explain the lack of power.
Boost leak test time?

[andy10v]

You got a leak tester Martin?

If not swing by sometime.

[Jamo]

down to nearly 9 AFR???? sweet jesus thats so rich the graph should be stamped bling

[martinws]

I thought so but wanted to check. Ill leak test then get it ran again. I have a kinda crude tester but might take the trip over Andy, ill let you know.

[prj]

If it was correctly holding boost, the AAN/ABY injectors are too small to even produce this amount of fuel.
So that means boost tapers off much quicker than it should also.

[Sonic]

down to nearly 9 AFR???? sweet jesus thats so rich the graph should be stamped bling

Indeed my eyes were hurting with the amount of fuel when mine was running 9 AFR.

[martinws]

If it was correctly holding boost, the AAN/ABY injectors are too small to even produce this amount of fuel.
So that means boost tapers off much quicker than it should also.

So unless iv got massive injectors(which i don't) there is a boost leak?
Ill need to find a way of testing my homemade inlet manifold for air tightness.

[elaw]

I don't know much about your setup but there are a number of other things that could cause this...

Bad chip (not defective but poorly programmed)
Chip designed for different setup (injectors/turbo)
Wrong injectors (larger than chip is designed for)
Fuel pressure too high

I guess #2 and #3 are kind of the same thing but you get the idea.

[andy10v]

I would leak test the whole intake setup Martin, you can fill a skooshy bootle with soapy water and spray areas down if its not obvious, injector seats et.

PRJ leak test

1. No need to pressure test over 15 psi.
2. No need to EVER remove the hose from the TB. If they have been doing that each and every time, that's exactly where they go wrong. 99% of all the boost leaks are things connected to the IM.

Look, taking the assembled car, the only things that have to be done are:
1. Untighten clip on MAF end of MAF->turbo hose.
2. Slide off the MAF->turbo hose from the MAF.
3. Fit pressure tester instead of the MAF into the opening.
4. Disconnect the PCV from MAF->Turbo hose.
5. Block the PCV on the MAF->Turbo hose end, leaving the other end (the metal pipe) open to atmosphere.

Now put 14psi in. Does it hold?
That's literally all you have to do. Not undoing ANY other hoses. Not undoing ANY vacuum lines, DV etc. EVERYTHING must be in place.
If they have each time been disconnecting the throttle body hose, then in fact they have not pressure tested the car at all. I have no idea why so many people keep disconnecting the TB hose.
You will also never hear anything about the recirc valve as it has the same pressure on both ends.

Elaw its an ABY in a type 85 90q running PRJ software, flipped intake manifold and custom exhaust, fmic etc.

[martinws]

Did a very brief boost leak test. I found there was a few small holes in welds on the inlet manifold and a leak on the throttle body gasket as well as leak on injector seals 2,4+5. I would have thought that this much leaking after the throttle body would result in a dodgy idle? but it idles fine. I also run an 044 pump but this should be fine with stock fuel regulator.

I checked this by blocking the MAF hose with a bung with valve on it, then used a double ended hose with valve adapters and attached it to a big tyre with 20psi in it. So never actually held pressure. Should it hold pressure even with valves etc open?

[HenryG40]

Apologies for hijacking the thread slightly - Does anyone happen to know where I can buy a bung with valve to suit an ABY MAF? I appear to be down on boost and figured this is the best place to start

Cheers

[martinws]

I made one with a bit for a toilet and a truck valve.