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B21Ft no power under boost

Murploid1

Murploid1

Member
Joined
Apr 6, 2017
Location
Houston, Texas
Hi all,

Car: 1982 volvo 244 TIC, manual boost controller, Do88 inter-cooler and hoses

Hoping someone can help shine some light on this issue...

Last week the car lost coolant (pipe popped off). I attempted to hobble home and the temp gauge went into the red, at this point the car was immediately stopped for 15 minutes until my wife arrived with some coolant. Coolant added and the car drove home fine (temp gauge read normal)

Two days later the car no longer pulls under boost. It stumbles and stutters as soon as the boost comes on. Sometimes it will hit 3500rpm and I get aaaaaaallllll.....the boost in one hit. Like 0psi - 18psi instantly.

Things I have checked
  • I did a compression check (good)
  • I took off all the boost hoses and checked them
    • They are good (I only bought them 2 years ago Do88)
  • Spark plugs looked fine but I may replace them in case?
  • Plug wires are 6 months old
  • I checked rotor cap and points (good)
  • checked for play in the turbo, spins freely and no play
    • CHRA is 6 months old
When I tested it last night I could swear I heard a boost leak, hissing when it built pressure. However, today, I can no longer hear any pressure escaping! Not sure what other if any hoses need checked?

Annoyingly my wide band is not working, as i would like to know if its fuel or spark - although it smells rich...

I am not sure if the previous issue (temp in red) is just a coincidence? Not sure if the turbo is blown? But there is no blue smoke from exhaust at all.
 
update: checked all plugs after driving again today - all completely black and fouled.

Pretty sure if I replace them they will just end up fouled again. Not sure whats causing this...
 
I think you should replace the plugs. Plug wires may have gotten roasted so they don't conduct very well anymore. Maybe check the plug wires resistance? If your boost enrichment switch is stuck grounded out that can also make for an engine that runs too rich. It's a blue switch on the firewall of the engine compartment. At 2.9psi it grounds out and enriches the engine mixture for boost.
 
How's your coolant reservoir look (fluid level low?/discolored/or contaminated looking fluid?/any gurgling/or pressure activity?) I think I'd do a block test to see if you have a blown head gasket. Sometimes a blown head gasket doesn't show up immediately. You probably have more than one issue going on. If you heard a hissing noise, under boost, previously, you've got a leak somewhere (maybe the intercooler, if all the hoses are ok). When you last drove it, and it didn't make hissing noise, did it get into boost at all? If not, it wouldn't hiss. Curious, what coolant hose blew off? How's your engine wiring harness (insulation coating)?
 
I changed the spark plugs; made no difference. I am going to look into the waste-gate make sure everything is functioning.

Coolant reservoir looks good, the head gasket was replaced 6 months ago (cometic). I would be shocked if my Do88 had a leak, but I can swap it out to test. I was getting spikes of boost when I drove it last, maybe to your point tbrcktch there was not enough to make the hissing sound.

I have driven this car with a blown head gasket in the past. It didnt behave like this. I have also driven this car in the past with a blown turbo and it did behave like this - I am starting to wonder if I cooked my turbo.

The hose that connects under the reservoir came off, my fault. The reservoir needed replaced (plastic pipe damage), I had the part and never got around to it, was always going to happen....

Engine wiring harness was replaced 2 years ago with a new dave barton loom..
 
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Update: Car has a boost leak - still no idea where. I unplugged the o2 sensor this allowed me to build a little boost. With it plugged in the car can barely go faster than 35mph.

When I hit 6psi of boost I can hear the boost escaping, hissing, and whooshing...

I have already checked all the boost hoses. Nothing obvious I can see. I guess the inter-cooler is next...
 
Can you tell, if hissing is in the engine compartment, or in the drivers side, above the pedal area, or behind instrument cluster? If your leak is at the intercooler, and there's no obvious darker looking area, usually at tank core seam, you can sometimes find it by spraying very soapy water on intercooler, and pressurize, or if you can, get it into boost long enough to blow some bubbles. Have you checked the waste gate to see if the linkage is broken, and the waste gate is just flapping with no control?
 
Update here is; cannot find a boost leak. Car will be smoked tested next.

With the o2 sensor unplugged seems to run pretty well, soon as it is plugged back in, barely runs.

O2 sensor was replaced with a brand new one - made no difference. Whats causing the car to run like crap with the o2 sensor plugged in?

Idle also seems to be hunting more than usual, also kinda confirms a leak?

Idle valve has been checked, inlet manifold gasket checked (sprayed carb cleaner around it)

Any thoughts? Why would the car run well with the 02 unplugged and like utter crap with it plugged in?
 
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You need to check your lambda duty cycle readings. Do you have a CI injection fuel pressure gauge set up? If so you should check your pressures. If not, you should buy one, and the fittings you'll need. Essential to properly fault trace a K/Jet with issues. It's mechanical injection, so most issues, if not a vacuum/boost leak, are fuel pressure control, and/or delivery. Do you hear the frequency valve operating?
 
tbrcktch said:
You need to check your lambda duty cycle readings. Do you have a CI injection fuel pressure gauge set up? If so you should check your pressures. If not, you should buy one, and the fittings you'll need. Essential to properly fault trace a K/Jet with issues. It's mechanical injection, so most issues, if not a vacuum/boost leak, are fuel pressure control, and/or delivery. Do you hear the frequency valve operating?
Click to expand...
Don’t disagree with any of that.

The frequency valve is operating.

However, surely this is an electronic fault? Car idles and boosts fine (not perfect) with the o2 unplugged. As soon as this is connected it all falls apart. The o2 sensor is sending a reading to the ECM which then adjusts fuel accordingly? Either that signal is wrong or the computer is doing something wrong?
 
What turbo? Original, or watercooled replacement, T3? Something newer?
If you have an integrated CBV, or an add-on CBV, check that it's not damaged and leaking sometimes.
 
bobxyz said:
What turbo? Original, or watercooled replacement, T3? Something newer?
If you have an integrated CBV, or an add-on CBV, check that it's not damaged and leaking sometimes.
Click to expand...
15G and it is water and oil cooled.

CBV is different from a wastegate?

Still not sure that would explain why it runs OK with the o2 sensor unplugged? Or air entering system that shouldnt be screwing up reading, which screws up what the computer is trying to do?
 
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Murploid1 said:
15G and it is water and oil cooled.

CBV is different from a wastegate?

Still not sure that would explain why it runs OK with the o2 sensor unplugged? Or air entering system that shouldnt be screwing up reading, which screws up what the computer is trying to do?
Click to expand...
Wastegate is for exhaust, CBV is for air. CBV reciruclates boost into the intake so it doesn't lose metered air, BOV vents to atmosphere.
 
Radtap said:
Wastegate is for exhaust, CBV is for air. CBV reciruclates boost into the intake so it doesn't lose metered air, BOV vents to atmosphere.
Click to expand...

I have a 15g installed, presumably this would be built in to the unit?

EDIT: I know what this is now, good shout. Worth a look, perhaps leaking...
 
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Another important part of the boost equation is the boost enrichment valve on the firewall. it's a blue valve that grounds out at 2.9psi to give enrichment. It does that buy causing the lambda computer to raise the dwell to 75degrees. Are your plugs rich and getting spark blowout under boost?
 
dl242gt said:
Another important part of the boost equation is the boost enrichment valve on the firewall. it's a blue valve that grounds out at 2.9psi to give enrichment. It does that buy causing the lambda computer to raise the dwell to 75degrees. Are your plugs rich and getting spark blowout under boost?
Click to expand...
I have purchased a replacement. Progress has been made; replacing vac lines and replacement o2 sensor has meant the car now runs well under boost.

Now, I am trying to figure out why the idle is erratic….
 
Revisiting this post as I believe I have found the root cause of the issue.

After many changes the car was running reasonably well, not perfect but well (with o2 plugged back in).
Today, after more tinkering - not the case. Boost issues again.

I found the source of the hissing sound, its the distributor. Video link below:

https://imgur.com/a/gxfvoUc

This would explain the issues under boost, presumably its not turning under vacuum as its leaking?

So, question is how do I repair that? Do I need an entire unit or??? I will also check the check valve (if its a part of the plumbing setup)
 
That is a vacuum advance under vacuum and then the unit retards the timing under boost. So you need a turbo specific canister. The internal diaphragm can fail so that I would suspect is the hissing of vacuum leaking.
 
Final update to close this off. Issues now seem to be resolved.

Parts changed:
  • Ignition distributor (suspected vacuum)
  • CBV (replaced with a nice billet forge)
  • vacuum valve for fuel enrichment (this was causing bigger issues than I thought)
  • numerous vacuum lines replaced
  • throttle body gasket
I had to re-tune the car; timing and fuel after all that - seems to be working very well now.
 
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