What does this sound like to you? (possible vacuum issue)

[Justin88na]

Alright, well I replaced my injectors about 2 months ago and I am running into an issue. Before I start going nuts on replacing hoses and the like I figured I would put this out there to get some possible insight.

Now I believe my issue(s) is vacuum related and has to do with the hoses when I removed/installed the intake manifold. With that in mind, here is the problem:

-I am idling high(1100-1200rpm) when I put the car into park from drive. The car will go automatically to 1200rpms and then slowly rev down to 1100-1000rpms. When I put it into drive, my idle speed is ~900rpm(normal right?)

Now I have adjusted the idle air control valve numerous times to get where I am today. When I originally put the car back together she was idling around 1300rpms.

-My other issue is that when I am cruising with light throttle and let off the gas, the car seems like its not getting enough air. It is very similar to if you were in a manual car and needed to shift up, but did not. Now it isnt as dramatic as that but very similar nonetheless.

I did already replace the hoses that were undoubtedly cracked or split when I did the injectors. Unfortunately I did break my brake booster hose and had to jimmy rig a high pressure hose inside of a hard hose in sections. Obviously this sounds like I have a leak somewhere in my vacuum system but where to start?

Thanks,

Justin

[Q45tech]

Before anyone can even begin to think about your problem, please provide a city and state- country as appropriate to understand ambient conditions.

Leaks are normally found with a stethoscope or ultrasonic leak detector.

[Justin88na]

Wilton, NH approximately 1100Ft above sea level, average temp this year ~mid 70's

[Infinitiguy19]

Hook up a Vacuum gauge from Advance Auto or Sears and look at the readings.

My 90 [208,000 miles]had the plenum apart to change a few hoses [some I believe for the
second time [78,000 miles]due to minor vacuum leaks. In the process I over tightened 3 of the
bolts which sheared [added a few hours of double work]. Always lubricate [antiseize] the threads
when reinstalling. It appears in hot climates [and Ozone] at least that many of the under plenum
hoses get marginal every 120,000 miles or so [6 years]......now I'm constantly washing my
engine/radiator/condenser to keep it clean but the soap is mild not any engine gunk cleaner
which might accelerate a hoses demise. The vacuum leak was minor 18" vs. 22" normal but this
was enough to stiff the self learning to 88% vs. 100 [IAAC 35% vs. 15%] and change the idle
injector pulse from 2.2 msecs to 1.9/2.0 msecs causing a minor roving lean miss with AC on at
idle. Why I recommend an inexpensive [$30] vacuum gauge as a critical home diagnostic tool.
But the good news was that all the plenum runner gaskets were in good condition just cleaned,
lubed, and reused. Carefully place a tee between the fuel pressure regulator vacuum line and
attach a Sears large diameter vacuum gauge. They make special thread/stud removal bits,
follow instructions. The gasket itself provides the sealing, use a torque wrench. {I didn't guess I
better quit the gym}.

7173 A simple vacuum gauge connected [or teed] to the vacuum line feeding the fuel pressure
regulator should read 17-18" minimum at idle warm or cold. If you disconnect the vacuum to
pressure regulator the fuel rail pressure will increase from 34 PSI to around 44 PSI causing a
13.7% increase in flow the ECU should respond by reducing the idle pulse width from around
2.2 milliseconds to around 1.95 - 2.0 milliseconds. Remember the ECU is designed to maintain
a preset idle rpm so more/less air or more/less fuel are all it has to work with.

Both are by Q45tech

[Justin88na]

Thanks Paul Wall, I'll go pick up a Vacuum Tester and get back to you guys

[Q451990]

Another trick is to spray various areas under the intake with brake parts cleaner or carb cleaner at idle. If there's a leak, it'll suck in the "fuel" and you'll hear the engine speed rise.

Good luck!

Heath

[Justin88na]

I think I figured out the problem. Its my TPS, when I removed the intake manifold, I did loosen the nuts on my TPS, but since I didnt line it up right when tightening it, it is a little off. I am going to look into this tonight.

-J

[lino]

Unfortunately I did break my brake booster hose and had to jimmy rig a high pressure hose inside of a hard hose in sections.

I broke that one too

[Q45tech]

TPS must be set /reset with Consult or volt meter as hot throttle closed must be 0.44 +- 0.02 volts no more than 0.48 absolutely

[Justin88na]

Thanks Q45Tech!

[Justin88na]

well.... it looks like I need a new TPS, at least I know the solution to my problem!