[NighTHawK]

Ok, i just bought my car a month ago, and im still getting it dialed in after replacing the head gasket. When im at WOT i get a slight hesitation at 3k, and then in first gear itll go to about 4500 before the boost jumps up to about 11psi (running 7psi, stock everything). I let off, and let it shift, then get in it again and it immediately overboosts. If i let off just a little the boost goes down a bit, but not to seven, and i get a lot more power than i had at WOT. Im pretty sure my cam timing is right, and my ign timing is close, but i dont have a light right now so im really not sure, checking this weekend sometime. Would ign timing cause this, is my cam timing actually still off (ive been working on it for weeks now), or do i have a bigger problem? Thanks to those who reply.

 

[Dave]

How are your vaccum lines set up? Whats controlling your boost?

 

[NighTHawK]

I dont know anything about my vacuum system, but everything under the hood is stock, so whatever normally controls boost is currently doing it. If you could give me specific things to look at/for it would be helpful because this is the first and only turbo car i've ever even looked under the hood of.

 

[Jckrieger]

When setting your cam timing, there are 2 arrows on the sprocket that should line up with the seam between the head and the cam bearing cap. Use a mirror to get a straight look at it, otherwise there's a good chance that you're 1-2 teeth off. Ignition timing can also influence the way the engine runs, so you'll want to get a $30 timing light and check the base timing (with the coolant temp sensor unplugged). If the oil pump has ever been removed from the engine, there is a good chance that the distributor won't be quite in the right spot when the timing marks on the side of the engine line up. This is why a timing light is a must.

 

[NighTHawK]

Ok, i have two questions that will either tell me what the problem is, or have me even more confused than I was originally: Does the computer use the vaccum system in any way to control ignition timing? would a vaccum leak going to the third vaccum solenoid from the rear cause an incorrect reading in my boost guage (3-4psi difference)?

it feels like overboost cut out, all power instantly gone, revs staying exactly the same, no loss in speed. But my boost guage reads a solid 7. Could this be ignition timing? I know its a solid 8 deg at idle, so it would have to be my LM malfunctioning or recieving incorrect signals. Could the PM cause that, because I've had issues with it before (ASD relay is fried, external one currently wired in). Thanks for all your help guys.

 

[Dave]

I dont know about the computer controlling the igniton timing via vac. lines.

And any kind of vaccum leak on a line that your boost gauge is hooked to will cause an incorrect reading because the air is escaping out and not going to your gauge.

Also, what kind of car is this? Ive been dealing with overboost for the past month...causes are: Massive boost creep (mitsu. and great exhaust dont mate well)..and now my Wastegate can is too tight.

 

[NighTHawK]

Its an 86 daytona T1, completely stock. Is 8 deg too advanced and possibly causing my problems? It feels like a rev limiter but i dont know if its not just a massive power problem at WOT or close to it. Also there's a lot of misfiring. Most of this doesnt happen when its cold, could be from the extra gas?

 

[daytonajesse]

do you mean 8 degrees advanced from the stock timing?

 

[NighTHawK]

The 8 in the window is lined up with my timing mark on the flywheel (when using a timing light, obvioulsy)

 

[Dave]

No 8 should be fine, that is close to stock.

You would know if it's overboost. If it's an auto. like Im assuming, then it will buck once then a second later do it again. If it's a stick, oh god you will know for sure, 5spds cut out a lot harder.

 

[TRRBOJEEP]

It sounds to me like your timing is fine. Timing won't cause boost to shoot up to 14.7psi (cut out level). If your boost is jumping off the charts, then most likely you've got a vacuum leak. As you stated it's all stock, which means those vac. lines under there could be the original ones. Most likely one, or more may be cracked and leaking. Go get some new vacuum line and start replacing them one by one, being carefull to hook everything back up the same way.
Let us know if that solves the problem.