what is a map bomb

[steve wiener]

what is a map bomb and how do you make one.

thanks

steve w.

[500dollar744ti]

a map bomb is vac/pressure reservoir installed inline with the MS map signal line, designed to smooth out the signal MS gets from the manifold.

[wennstroma]

You can make one out of pvc plumbing pipe (2" diameter) and two end caps. You don't want to make it very large, just the length of the two end caps with the pipe glued inside.

When I installed mine inline it made the response too slow. It worked better to tee it into the vacuum line, just enough to "dampen" the signal.

I don't even use it anymore though.

[towerymt]

You can make one out of pvc plumbing pipe (2" diameter) and two end caps. You don't want to make it very large, just the length of the two end caps with the pipe glued inside.

When I installed mine inline it made the response too slow. It worked better to tee it into the vacuum line, just enough to "dampen" the signal.

I don't even use it anymore though.
Same experience here with the map bomb. I made mine from 2" PVC, about 5" long. I could have made it ~3/4" shorter if the two caps were touching. The response is really poor now. I'm going to try teeing into the line for the boost gauge to pull the signal for the MS box and hope that it helps enough to smooth the idle just a little bit.

[JohnMc]

Same experience here. Put it in, car ran wonky, took it off, ran better. Looked at logs, saw no flakiness in MAP signals in the first place.

I'd only bother with it if you are actually having problems that look like jumpy MAP signals might be the cause.

[jimjawz]

I once used an older style plastic fuel filter inline. this cleaned the signals but know i use a longer piece of vac line to gain the response back.

[The Aspirator]

Here's my map bomb, I've had it in for over a year and I think it really smoothed out my map signal, works perfectly for me! Now I just have one thickwalled vacuum hose coming from the manifold into the map bomb (top), then boost gauge, heater vents, and megasquirt MAP signal coming out the sides.

John

http://www.cravingboost.com/cars/megasquirt-mapbomb01.jpg

[JohnLane]

Those of us needing a MAP bomb.... This is for idle only?

Are you unable to tell MS to give you X for fuel at idle and turn off closed-loop operation at idle?

The fuel curve should be just fine if you've got your temp enrichments done right.

Electromotive lets me set the 'rate of change' for MAP and TPS so that I can make a smooth idle and not have excessive enrichment.

[The Aspirator]

No John it's mostly for people that can't get a smooth map signal, like it'll look all lumpy on the datalogs, and this can trip off acceleration enrichments at idle, and sometimes even at cruise or full boost.

[benflynn]

urban legand

[gsellstr]

Urban legend my arse.

The map signal on the 140 would jump around a good 10-15kpa just because of the motor's build. I actually used the plastic tank from the EGR amp from the car. Tried running it inline and got really sluggish response. T'd it in and it smoothed stuff out a lot (3-4kpa fluctuations now). I was getting the accel enrichment kicking in at idle as well.

[The Aspirator]

urban legandYou're an urban legend. Ha!

[steve wiener]

thanks for all your responses,my situation is alittle different.my 83 244 turbo now has a 87 police 350 with a gm hot cam edlebrock aluminum heads and a chipped tbi,so i might need a map bomb because i have a lumpy idle.

steve w.

[wennstroma]

urban legand

It really helped on my old engine. It was worn mechanically so the idle map was not steady. With the new engine I don't need it though.

I also see them used on cars with ITBs, to link all the cylinders together.

[The Aspirator]

Only if your ECU actually uses a map signal, if it's AMM based then there might not even be a vacuum line going to the ecu. I dunno anything about v8's though, sorry. Sounds like a fun car though!

[steve wiener]

im using a gm tbi system which uses a map sensor so yes it will help me dial it in.thanks for the info,ive been a volvo tech for 23 years and its definatly the fastest volvo ive ever driven.makes an R seem like a slug that wont turn.

steve w.

[benflynn]

should ride in a volvo from bama