Boost/vacuum not reading on cold start

[eriesupra]

When I cold start my car the boost gauges do not read anything until the cars warms up, the stock gauge too. They are fed from the stock fpr. I say they because I have a autometer and a profec b. After the car warms up they seem fine.

Is this normal or what should I check?

Just bought my 88 Supra a couple of months ago and have been trying to learn more about the car but I come from a DSM so things are a little different.

 

[suprasnd]

When I cold start my car the boost gauges do not read anything until the cars warms up, the stock gauge too. They are fed from the stock fpr. I say they because I have a autometer and a profec b. After the car warms up they seem fine.

Is this normal or what should I check?

Just bought my 88 Supra a couple of months ago and have been trying to learn more about the car but I come from a DSM so things are a little different.

When if any, did you do any work on your car? Do you have aftermarket gauges. If so what is vacuum reading when cold? I assume the autometer is a boost/vacuum gauge? What is reading after warmed up? I also am in PA. PM me and I could give you a contact number to talk you through this matter. If you would like.

Keith

 

[eriesupra]

When if any, did you do any work on your car? Do you have aftermarket gauges. If so what is vacuum reading when cold? I assume the autometer is a boost/vacuum gauge? What is reading after warmed up? I also am in PA. PM me and I could give you a contact number to talk you through this matter. If you would like.

Keith

I have an autometer pro-comp lite. When the engine is cold it doesn't move at all. It holds steady 21 at idle when warmed up.

The only thing I have done since I bought the car was change the oil, remove the bosch platinum plugs and installed NGK plugs and install the profec b. The car had the timing belt and headgasket changed less than 20k miles ago and runs good otherwise. Except that I haven't been able to get it to boost much past 9.6 psi with the profec b installed, I was trying to get 10.5 or so. I have it set to psi 20% 15%gain 7 set gain 11 limit 16% cutbak. I tried upping the settings but it didn't seem to make a diff.

The car has an HKS 3" tubo back exhaust with cats, K&N intake and some aftermarket blowoff valve that I don't see any markings of any kind on it.

 

[suprasnd]

I have an autometer pro-comp lite. When the engine is cold it doesn't move at all. It holds steady 21 at idle when warmed up.

The only thing I have done since I bought the car was change the oil, remove the bosch platinum plugs and installed NGK plugs and install the profec b. The car had the timing belt and headgasket changed less than 20k miles ago and runs good otherwise. Except that I haven't been able to get it to boost much past 9.6 psi with the profec b installed, I was trying to get 10.5 or so. I have it set to psi 20% 15%gain 7 set gain 11 limit 16% cutbak. I tried upping the settings but it didn't seem to make a diff.

The car has an HKS 3" tubo back exhaust with cats, K&N intake and some aftermarket blowoff valve that I don't see any markings of any kind on it.

Almost sounds like your vacuum line that is switching the VSV is not working properly. Your awesome on vacuum when warmed up. I boost 10psi with HKS F-Con installed with no boost controller. Boost response is nice also but not like when Profec hangs wastegate shut longer. Also check that that BOV isn't leaking under boost. That may be Y you can't get beyond 10.5. I've gotten 17 with profec in my car once because my oldest son pushed the high button and turned it all the way up. Figured that one out pretty quick. On a stock CT also.

Keith

 

[eriesupra]

Almost sounds like your vacuum line that is switching the VSV is not working properly. Your awesome on vacuum when warmed up. I boost 10psi with HKS F-Con installed with no boost controller. Boost response is nice also but not like when Profec hangs wastegate shut longer. Also check that that BOV isn't leaking under boost. That may be Y you can't get beyond 10.5. I've gotten 17 with profec in my car once because my oldest son pushed the high button and turned it all the way up. Figured that one out pretty quick. On a stock CT also.

Keith

Here is a link to a pic of the bov http://mysite.verizon.net/gfalbert/bov.JPG

Can you tell what brand it is?

 

[jetjock]

The gages should be connected directly to the intake manifold. That way they won't be effected by the Fuel Pressure Up system, which appears to not be working correctly.

 

[supraguy@aol]

The gages should be connected directly to the intake manifold. That way they won't be effected by the Fuel Pressure Up system, which appears to not be working correctly.

What he said.
It struck me as strange that you had your gauge hooked to the FPR line instead of the manifold.

 

[mkIIIman089]

The gages should be connected directly to the intake manifold. That way they won't be effected by the Fuel Pressure Up system, which appears to not be working correctly.

Only took 6 posts...

 

[eriesupra]

This was the way the gauge was hooked up when I bought it, though I thought that was the common place to tie in to?

What is the deal with my "fuel pressure up system", what does it affect?

 

[jetjock]

When the coolant is hot the ECU disconnects the fuel regulator from engine vacuum and bleeds it to atmospheric pressure for about 2 minutes after a hot start. It does this by using a three way vacuum switching valve located under the intake manifold. This raises fuel pressure and clears any vapor in the fuel lines that may have formed during heat soak. That's why connecting the gages to the fuel regulator is a bad idea. That said this action should only occur when the coolant is hot so doing it on a cold start is odd.

Connect the gages directly to the manifold, say using the nipple on the rear of the intake plenum. Then either troubleshoot the FPU system or delete it altogether by also connecting the fuel regulator directly to the manifold. You can do that by removing the VSV and connecting the two hoses together. The VSV is behind the alternator.

 

[mkIIIman089]

It says in the manual of every boost referenced piece of electronic gadgetry I have to tap directly off the intake manifold. Whoever installed it is just an idiot.

 

[eriesupra]

Thanks guys!

Anybody look at that pic of the bov and venture a guess as to who makes it? I'm just wondering if it is some cheap Chinese piece that I should replace.

 

[mkIIIman089]

Looks like a chinese piece to my relatively uneducated eye...

 

[suprasnd]

Thanks guys!

Anybody look at that pic of the bov and venture a guess as to who makes it? I'm just wondering if it is some cheap Chinese piece that I should replace.

More of a bypass valve than a BOV. I would ditch that for a good one. Never seen one or ever seen anything that looked like that thing. JMHO.

Keith

Make sure your fuel pressure up system is working as you can do serious damage to engine by starving it with fuel. Are you hitting fuel cut at all when you try to adjust the Profec to a higher boost or does the car have FCD installed?

 

[jdub]

Make sure your fuel pressure up system is working as you can do serious damage to engine by starving it with fuel.

Say what?!?!



The fuel pressure up system is only suppose to work when the engine is hot...you could actually disconnect it and likely not have a problem. It is there to clear the fuel system of any vapor like JJ said...a hard start on a hot summer day comes to mind. I'd like to hear how this could possibily cause damage to the engine.

 

[jetjock]

Yeah, I explain how it works and that gets posted. Amazing. There's been a huge amount of stupidity around here lately. For the last few weeks it's been post after post of nonsense. It's why I took a break. Perhaps it's time for another.

 

[suprasnd]

Say what?!?!



The fuel pressure up system is only suppose to work when the engine is hot...you could actually disconnect it and likely not have a problem. It is there to clear the fuel system of any vapor like JJ said...a hard start on a hot summer day comes to mind. I'd like to here how this could possibily cause damage to the engine.

My bad. Slight misunderstanding. Sometimes what I think and my hands type don't always come out right. :1zhelp: