My 1997 6.5 run great until I hook up to my 6500# 5th wheeler. My boost gauge shows boost at the start, then something shuts it right down around 7psi. If I keep my foot on the gas the boost will NOT come back, only when I let my foot complety off the acc. will the boost come back, like the compter resets, but then only to fail again at 7psi when I hit the acc. again. Changed MAP, Boost sens. new PMD with cooler, vac lines tight, I was wondering what other sensors the computer uses to determin to defuel-deboost my little truck. Mabey a transmission sensor, oilpress sensor, temp sensor?

Put a 3bar MAP on. It's calibrated to allow 3x barometric without a DTC for boost.

The stock system doesn't like more than 8 psi sustained for 20 seconds and tries to lower WGDC (the rate of pulses to the solenoid) then pulls all vacuum to turbo and sets SES light. It's also possible the solenoid is faulty. Have you measured vacuum at the turbo?

QM, what do you like better, resistors soldered in or the three BAR map? :confused:

If I had $50 and a working MAP, I'd soder resistors in, but not every guy is going to get this right or up to code (he he) and I think it's best to have it as simple as possible and internal resistance in the MAP is the simplist means to an end that anyone should be able to get right without further adjustment.

Thanks for the info. You are talking about the map that monitors boost pres on the intake right. There is another map that monitors vac in the egr system, and altitutude before start. I was going to give up on the whole thing and buy a turbo master, but I thought the computer would still de-fuel, but only after 7psi right? What if i would to remove the map so the thing always reads atmosphere pres, then wire up the waste gate, or go with the turbo, is the map the only thing that monitors the boost pres?

Abel the 3 Bar Map or resistors will give added grunt, but you need to open exhaust and some other things before the truck is safe to take on more boost. I can't repeat this often enough too many have done it the wrong way.

DO NO ALTERATIONS THAT ALLOW DELIVERY OF MORE FUEL, BOOST, OR TIMING WITHOUT GAUGES INCLUDING EGT

Depending how far you go with a TM PCM may code and defuel as high IAT is something that will defuel; as will, a very high offset of rpm vs fuel vs boost (too low for power level if MAP is fooled too much) reflash or chip puts things in balance so you don't code or defuel. You can add some boost with a TM without gauges but I'd run at minimum recommended setting and buy a complete set of gauges at 1st opportunty.

Oh BTW welcome to the site, spend some time in FAQs sticky thread, and update your sig per welcome notes looks like you are S engine but I can't be sure check your VIN 8th digit F or S there tells us a lot how to better advise you.

Now that you mention EGR I think that you should test for vac at the baro(map) on the frewall the ECM is looking at on an S engine.

with my 97 and a resistor on the map and the turbomaster w/stock spring, i get all the boost i need. follow turbine docs advice about the exhaust and gauges first. then you can increase boost. after you get these mods and are ready for more boost, the 3bar map is defintely an easy and cheap solution.

my truck will run from 3-5 psi unloaded and around 8-10 psi loaded, on flat ground. if i hit a hill i can get up to 13-15 pounds when i need it.

but i have a question. i have read on here several times about max sustained boost of 10 psi for non-intercooled. how long does sustained mean?

From a dead stop, unloaded, 15-20 psi will get you to 70 mph in 15 seconds or less. Unless you're racing uphill I don't see how you can sustain that.

You can't tow with 10+ without post turbo cooling and not have problems down the road; and shouldn't race or daily drive that way physically you can do it just not best IMO , sustained is hill climb while towing or trying to maintain 70+ mph with a heavy drag load is when you need IC or WMI to keep IAT in check , high IAT causes everything else to go high as well, more involved than that but basic enough info as to why you should not do it,.

Turbine Doc,
Will check the vac at baro(map). From other readings on the site I've heard that baro map can cause problems if vac's are out... I'm not really looking for big power, my truck will pull the trailer when everything is in sink, but when the boost comes and goes( usually in hills) it becomes annoying. Built myself a home made TM, running at 4-5psi on cruise, 6-7 on pulls, seems to help. Thanks for the help. Did they upgrade the waterpump on the 97's, and how does the massflo air sensor play into the BIG picture?

Abel update your sig your being a S truck with MAF is an important piece of info we need to advise you. Yes 97 is year dual thermostat & HO watewr pump showed on the scene.

PM me and I can give you some S engine tips to get you a little more power until you start adding mods.