Code 45 Turbo Boost Limit Exceeded

[JCI400]

Its been 10 years since the Mini-mopar site was last updated
(thank you Russell W. Knize, the site has been invaluable, my car runs because of your web site and TurboDodge.com)

Is there any updates for code 45 or procedures to test/resolve that have been discovered since then?

Work to date:
Replaced PM and LM
Replaced Dist Ignition Pick-up, Plugs, wires, rotor and cap
Compression is 130-135 in each cylinder
Fuel pressure is 47 (disconnect vacuum from reg and jumps to 55)

This eliminated codes 15, 24 and 54 as well as the dreaded limp-in mode

[JCI400]

One other thing... This is my first turbo four

I jump on it there's 4.5 seconds of turbo lag.

Related to code 45 or is this normal for the little turbo that could ?

[EvilcowRoland]

That could be related sure. You're getting code 45 because the computer has detected a high boost condition (exceeding 14.7 PSI or 2 bar's of pressure). The stock MAP is only designed for 2 bar operation and cannot read past that. If you have a stock '85 T1 then you should only be boosting about 7 PSI. If you have modified your car to boost higher then you need to either adjust the boost back under 14.7 PSI or switch the computer and MAP to a 3 bar system to read the higher boost. (Don't forget to add more fuel if you do). More info on your car is needed to determine why you are lagging, but usually it's a restriction in the system or a vacuum problem. With a stock '85 Garrett T1, you should be seeing max boost around 3000 RPM ideally. With an open exhaust it would be lower.

[JCI400]

Car is completely stock (for the moment), so how could it be overboosted?clogged cat,
vacuum issue,
dead wastegate and/or selonoid,
or what else?

What have you guys on the forum experienced on code 45?

[boostedhatch]

Quote:

Originally Posted by JCI400 Its been 10 years since the Mini-mopar site was last updated (thank you Russell W. Knize, the site has been invaluable, my car runs because of your web site and TurboDodge.com) Is there any updates for code 45 or procedures to test/resolve that have been discovered since then? Work to date: Replaced PM and LM Replaced Dist Ignition Pick-up, Plugs, wires, rotor and cap Compression is 130-135 in each cylinder Fuel pressure is 47 (disconnect vacuum from reg and jumps to 55) This eliminated codes 15, 24 and 54 as well as the dreaded limp-in mode

Check vac lines my shadow did the same thing or it could be wg stuck or worn out.Grab you wg arm and see if you can pull it out some.You can also add in extra vac line going to your wg

[EvilcowRoland]

The way the turbo wastegate works is something like this: There is a small flap inside the exhaust housing of the turbo. It is held open or closed by an arm and a spring actuated canister. You can see this can/arm combo on top of the turbo. It has a vacuum fitting on it. When boost pressure is applied to that fitting and it exceeds the spring pressure in the can, it pushes the flap open, disallowing the turbo to build any more boost. The default pressure on a Garrett like ours is about 5 PSI. To make your car build more boost than that, there is a computer controlled solenoid on the passenger side (wastegate solenoid) that delays the boost from reaching the canister. As the computer gets readings from the MAP sensor, it can tell the wastegate solenoid to open at higher boost levels so that the wastegate armiture only opens at the higher levels. This should occur at about 7 PSI. Now, if you have a leak somewhere in the system and the boost pressure isn't allowed to open the wastegate flap, the turbo will keep building boost (for example, removing the vacuum line to the can). That's bad for you because your car isn't tuned for that. Step 1 is to stop boosting that high before you cause damage. Step 2 is to examine your vacuum system for any leaks. Check for holes, cracks, broken or disconnected lines. Your problem is likely in the wastegate control vacuum system. There should be a vacuum line going from the intake manifold to the top port of the wastegate solenoid and then another line from the middle port on the solenoid to the wastegate can port. Check all of your vacuum lines first and you can even try moving the wastegate arm by hand like boostedhatch said to make sure the flap isn't stuck. If everything looks good then you may have a bad wastegate control solenoid. You should have a vacuum diagram under your hood to help you identify where things are and where they should go. You may also want to install a boost gauge to make sure you don't overboost anymore while testing. With your T1 car, you probably shouldn't go past 10-12 PSI for safety reasons.

[mmtphoto]

does code 45 clear itself after multiple starts like other codes? I did an overboost (45) ONCE, and don't want to disconnect the battery, takes 20 minutes to reprogram the Sony cd (30 stations, clock...I know, I'm lazy)-I promise I won't overboost again

[EvilcowRoland]

I don't think that code will clear itself no. But you could get one of those clock saver things that plug into the cigar lighter and then clear it. Just a thought.

[mmtphoto]

I don't think that'd work, since it would provide power to the ecm too-it is not really a big deal, I know why it's there (had the boost controller a little too aggressive), and anyway I know that a code 12 has gone away if it does not reoccur within about 50 starts. Like I said, just being lazy, I can just reprogram (again) the head unit.

[JCI400]

If I move the vacuum fitting from the bottom of the selonoid to the top, the wastegate is always open, no power no error.

Move it back where it belongs and I get code 45 - overboost.

Seems like the wastegate and vacuum lines are OK and the selonoid is bad.

Where can I find the right selonoid, what do I ask for?

[EvilcowRoland]

It's just a univeral vacuum control solenoid. IF you can get one through the dealer, it'll be a wastegate control solenoid. But I don't think they have the specific ones anymore. Best bet is to try to find one from the junkyard. Or for that matter, switch it with the purge solenoid if you aren't worried about emissions. Or get a manual boost controller and don't use the wastegate solenoid at all. Lots of options for you.

[crusty shadow]

just get a simple manual boost controller. and a boost gauge! guy on ebay NSX motorsports has a nice little boost controller- very similar to the G valves mentioned on here, but better- easier to adjust. i paid 15 bucks for mine, works perfectly. since you have a TI you will get overboost codes sooner than 14.7 psi- you'll be hitting em at 12 psi or 10 psi depending on the car. i wouldnt go past 10 psi on a TI anyway, you should really have an intercooler and a different computer if you want more than that.

[JCI400]

Sorry, I'm a big block guy. Explain it in smaller words.

Manual boost controller will still freak out the computer. Do I now have to replace the LM?

If I move the wastegate vacuum line from the bottom of the selonoid to the bleed on top, the wastegate is always open. No boost no code. But proves the vacuum lines and wastegate work. Moved the wastegate feeds to Purge Selonoid, same thing happens, code 45 overboost.

Either both selonoids are dead, ground isn't, or the computer isn't sending the signal. Hopefully checking all of the above and the amount of boost tomorrow. Suggestions very welcome.

Like the boost guage idea... and a tach.

[EvilcowRoland]

Um, okay I guess I needed to explain more. I meant switch the solenoids in location, meaning the electrical plugs too. The solenoids function the same, but they are controlled by different circuits. A manual boost controller won't hurt the system as long as you don't turn the boost up too much. Set it to 10 PSI and forget about it.

[JCI400]

Thanks Evilcow. Now I understand what you guys have been talking about.

So I still need to figure out my selonoid problem, which as my post above says, I think is electrical.

I'm a so:

In testing, I can take a connection thru a meter to a ground to look for voltage without damaging anything, right? This is new ground (sorry for the pun) for me. I would hate to short out something valuable.