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Boost pressure drops.

Just a thought, does performance drop off and smoke develop out the tail pipe when boost drops?

My gauge was acting up and it turned out to be a pinched hose in the pillar.
 
Codes? and where are your heater core hoses running off to?
PMD would be happier outside engine bay.
 
Burning oil said:
Codes? and where are your heater core hoses running off to?
PMD would be happier outside engine bay.
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It has a Webasto heater added to it. Sometimes, in winter time, night can be very cold over here like -35 F. I also have Wolverine electric heater under engine oilpan and transmission oilpan.
 
THEFERMANATOR said:
For starters that isn't a 95 engine, and yes it's an S engine. It is at least a late 96 or newer engine fro mthe A/C compressor on the left side and the dual t-stat housing. This engine is in a SUBURBAN?
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Yes, this engine is in Suburban K1500. VIN indicates it is 95 model. Maybe the previous owner has swapped the engine. I do not know. Everything have worked so far. I`m heading to the garage and check engine codes and let You know whats in there.
 
Looking closely at your pics raises even more questions. K1500 BURBS even in 96-99 didn't have S engines in them. You have the 3 solenoids(1 for wastegate control and 2 for EGR), but only the wastegate one is plugged in. I see 2 baro sensors on the firewall both with hoses hooked to them. 94-95 F engines had 1 on the firewall with no hose hooked to it, 96+ F engines didn't have one on the firewall, and the S engines from 94-99 had one that was hooked up to the vacuum supply(the blue hose). Your A/C system is definitely 96-99 as GM didn't even make that A/C compressor until 96, and your turbo is either a GM5 or GM8 which didn't come out until 96. Your pictures don't show the intake to tell if it has a MAF or not, but if it does that also didn't come out until 96 for S engines ONLY. Looks to me like you have a BURB with an engine swap in it to me from what I can see. Try taking the blue hose off from the firewall mounted sensor and plug it with a bolt or something and see if it will hold boost then.
 
I checked the engine codes, only 12. Nothing else. There was a MAF in the intake, just after the airbox. I removed it because there where no connections to it. So, it seem that I have engine swap. The baro on the right in the firewall, is for Autometer boost gauge. I ordered new vacuumpump, liftpump, MAP which is located in te manifold, just in case. Tomorrow I will get a gauge that I can hook up to get vacuumpump + liftpump readings.
 
If the MAF wasn't hooked up along with the EGR solenoids being unplugged, try unhooking the blue vacuum line from the firewall mounted baro sensor and plug it off. Drive it and see if you have boost back. It's starting to sound like somebody swapped in a 96-99 S engine into your older BURB.
 
Just a thought. You mentioned this started happening after shorting out a battery. You should descibe the details of that incident as in there lays a clue. I haven't read through this yet so someone probably said it already. Disconnect your battery for 5 minutes let the system null and then reconnect and reboot and see if it helps at all. I believe there is a diode and a transistor on the PCM board that buffers the quad that could blow if it got reverse polarized in some way,, like a short!!
Everything else in the chain seems logical to check vacuum pump, line, boost solinoid or vacuum switch, line to actuator and actuator lever/diaphram and the manifold pressure sensor. You may have to get the turbo trigger out of the PCM on a scope to see if there is a control signal problem. I believe the problem is electronic in nature.
Other possibility would be a transmission code if you have an electronic 4l80 which may or may not pop the light on. Like something in the range switch or tcc but then you might get limp mode i think. Not sure but anyway i think the short fried something.
 
I will unhook the baro on the firewall to see if it helps. Connections has been like these always, no problems with anything.

The problem starded after the battery short circuited. I eas driving home and volt gauge started to travel and when of the throttle, battery light came on. When I got home, I opened the hood and right side battery, Optima, was blowing steam. Battery was very hot. I disconnected cables. I measured right away left side battery and it seemed ok, no over charging. I took of the broken battery and altenator and replaced them with new. Car stayed couple of days with out connected to the batteries.
When everything was hooked up back, old + new battery + new alternator, everyhting worked except boost when I accelerated hard. Now new boost solenoid, no changes. When I get he new MAP, I will change it also. Is the partnumber same for the MAP over the manifold and one on the firewall ?
 
Sounds like a serious short. I thought you just had some sparks when connecting cables.

The sensor on intake is a pressure sensor, one on firewall is vacuum I dont think they are the same.
 
The sensor in the intake is a 2 bar MAP sensor, the firewall mounted one is a 1 bar MAP sensor. They will not interchange. Just unhook the vacuum line from the firewall mounted one and plug the blue hose off. The firewall mounted sensor needs to be there, but referencing atmospheric pressure if it is an F engine calibration in the ECM.
 
THEFERMANATOR said:
The sensor in the intake is a 2 bar MAP sensor, the firewall mounted one is a 1 bar MAP sensor. They will not interchange. Just unhook the vacuum line from the firewall mounted one and plug the blue hose off. The firewall mounted sensor needs to be there, but referencing atmospheric pressure if it is an F engine calibration in the ECM.
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Thanks for the advice. I will try that one tomorrow. I was driving the car today, first, everything worked more than fine, boost went up on acceleration and stayed there. It was a happy time. The car sat hour and half on a parking lot. I headed home, same problem, on acceleration boost rises then drops to nearly zero. Can I take all the solenoids off, just leave the boost solenoid and single hose to the manifold top to that valve ?
 
Today I took of the hose to the baro on the firewall, plugged the hose and drove to the part shop to buy vacuum / pressure gauge. No changes. Then I measured vacuum pump. Needle bounced between 5 - 12. I think it should be constant. When I measured, I wasn´t driving and car was idling. Is that enough to determine that the vacuum pump is bad apple. Anyway, new is on the way.
 
FarmerJoe said:
Today I took of the hose to the baro on the firewall, plugged the hose and drove to the part shop to buy vacuum / pressure gauge. No changes. Then I measured vacuum pump. Needle bounced between 5 - 12. I think it should be constant. When I measured, I wasn´t driving and car was idling. Is that enough to determine that the vacuum pump is bad apple. Anyway, new is on the way.
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yes, that is way low, should be around 20-22" I think....
 
Take and check the vacuum directly at the vacuum pump. it should be at least 15 inches, but 20-22 is ideal. It isn't uncommon for a vacuum line to crack on these older trucks.
 
Do you know Pasi in Finland? He has a diesel shop and stocks vac pumps. I also have a few.
 
I do not know him, but I have bought a PDM and some other parts from him. He is located about 200 km from my place.
 
This is not funny anymore :errr: Since my last post to this problem, I have changed boost solenoid, vacuum pump and manifold MAP sensor. I have checked all the wiring + connectors. I have checked all the vacuum lines. I have checked everything twice and replaced the boost gauge. When I replaced the boost solenoid ( second one. first was aftermarket, now I have OEM ), I thought it got better. Boost didn`t drop any more. It went up to .8 psi when I accelerated and dropped to .4 and stayed there. I wasn´t happy about it. I changed the vacuumpump because vacuum it produced was too low. After that no changes. I changed MAP sensor, no changes. After couple of days and 300 kilometers it suddenly went better. Now when I drive and accelerate, boost goes up and stays .6 psi and it feels much better. Now it is like it used to be. Is it somekind of self learning when it comes to the boost pressure ?
 
Sounds like the new vac pump fixed it. Treat it like a woman: don't ask why and be happy.
 
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