North American Turbocoupe Organization



Help - Low Vacuum - long
Pete D Offline
Administrator
#1
I'm fighting a low vacuum problem in the project car. At warm idle the car pulls about 15" It used to pull between 15.5 and 16' but has never pulled the 17" others get with this cam. It is an 88 with the manual heat/AC and that may be important. I have removed the main feed hose from the upper intake to the vac tree and applied vacuum to the intake end, thus applying vacumm to pretty much the whole vacuum hose system. I can get about 15" and it bleeds down to < 5" in about 40 seconds or so. Doing the same to my other car I can pull 20+" and it holds. So I started doing the individual systems and I have a couple questions. The car that holds20+" also has the EACC.

1. On the project car (manual heat/AC) the is one of those hard plastic vac lines the goes through the FIREWALL near where the AC lines go through. What is that line for? It is not present on the other car that has the EACC.
(this line is holding good vacuum)

2. On the problem car there is also a vacuum line that goes through a hole in the passenger side INNER FENDER, right under the coil spring for the hood. This line will not hold more than 20" but it will hold it. What is this line and where does it go? Can you tell me why it holds 20" but no more? This line is not present on the other car either.

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NATO Member. it's not a vice, it's an obsession
"The nice thing about each new day is nobody ever used it before" Barnaby Jones
88 TC X 2, 86 SVO, Main TC with K&N, 3"DP to 2.5"duals through Dynamax, Ric valve at 17+ and disconnected KS. Elite Bodega 16" chrome wheels. Autometer pod w/ A/F and Vac/boost gauges.140 mph Motorsports Speedo New engine: Total Seal rings and TRW pistons, ported and polished head w/ cc'd chambers,1.59"exhausts, SS valves, gutted upper, knife edged lower, A-230 cam, Race Engineering Adj Cam Sprocket, Crowlers, ARP head studs, and rod bolts. Walbro 255 HP pump and Kirban adj FPR, T-3. Centerforce II, KB subs and jack rails.

[This message has been edited by Pete D (edited 04-28-2002).]
Pete Dunham


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GARNET88 Offline
Senior Member
#2
Try a leek check, useing acedalien gas or hook up to a smoke machine. You may detect a leek this way! Sory I can't help mutch more than that.
1988 Turbo Coupe
2.5" Stainless exhaust. Duals with flowmasters.
House of Kolor paint by: Glen Gordon
ROH Wheels
Lowered
Front Mount IC
Turbo Smart BOV
Gillis Boost valve
K&N
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fordtech58 Offline
Member
#3
Pete, I believe the vac line that goes through near the a/c lines is the feed for the manual a/c control head which uses vacumn to switch some or all of the blend doors. The one going into the right fender area I think goes to a vacumn resevior for the speed control its about the size of a softball. I don't have a clue why it would hold 20" fo vac and vent above that. Rick B.

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Pete D Offline
Administrator
#4
Garnet, I did hook a smoke machine (me [Image: biggrin.gif]) up to some of the vacuum lines, but it didn't really help. See below. Thanks. What is acedalien gas, never heard of it?

Fordtech I've done further testing and found that the speed control resvoir - IN THE DRIVERSIDE FENDER) is leaking somewhere. I tested it by disconnecting the hose to it at the three way valve under the tree. It looses vacumm in about 20-30 seconds where as the other car doesn't lose it faster than 5" in 1 minute. I took this line out of the circuit and blocked it off and it didn't improve my vacuum reading with the car running. However, the line I was asking about is on the PASSENGER side fender under the hood spring.

I'm actually fighting 3 problems; 1: low vacuum. 2. A whistling noise that changes pitch with rpm change and starts just after throttle tip in (say about 1500 rpm on up). It also continues for a brief few seconds after the throttle plate is closed. It happens under all rates of acceleration, from lightest to hardest. This has been going on since I put a new cartrage in the turbo, reusing my old housings.The whistling is very pronounced inside the car under load (driving it) and almost impossible to hear parked, free reving the engine while listening under the hood. 3. My A/F gauge changes up and down like it should at idle but as soon as the throttle is tipped in it goes to slightly lean and holds steady - again, at any rate of acceleration.

I've had the turbo checked, but not torn down and I did replace the large diameter gasket between the back plate and the compressor housing. Ive checked the VAM to turbo hose and the I/C hoses, a couple times. I have checked and smoothed the mating surfaces for the TB and both ends of the upper intake, new gaskets and blue goo. New gaskets for the IAC and TPS and checked the seals in the TB.

I think the low vacuum and the A/F problem may be related although there is a high likely hood that coolant fumes may have contaminated the O2. The O2 was new Ford 5K miles ago. I'm going to pull codes as soon as I post this.

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NATO Member. it's not a vice, it's an obsession
"The nice thing about each new day is nobody ever used it before" Barnaby Jones
88 TC X 2, 86 SVO, Main TC with K&N, 3"DP to 2.5"duals through Dynamax, Ric valve at 17+ and disconnected KS. Elite Bodega 16" chrome wheels. Autometer pod w/ A/F and Vac/boost gauges.140 mph Motorsports Speedo New engine: Total Seal rings and TRW pistons, ported and polished head w/ cc'd chambers,1.59"exhausts, SS valves, gutted upper, knife edged lower, A-230 cam, Race Engineering Adj Cam Sprocket, Crowlers, ARP head studs, and rod bolts. Walbro 255 HP pump and Kirban adj FPR, T-3. Centerforce II, KB subs and jack rails.



[This message has been edited by Pete D (edited 04-28-2002).]
Pete Dunham


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segfaultxr7 Offline
Posting Freak
#5
Quote:Originally posted by Pete D:
I think the low vacuum and the A/F problem may be related although there is a high likely hood that coolant fumes may have contaminated the O2. The O2 was new Ford 5K miles ago. I'm going to pull codes as soon as I post this.

I'd normally think so too, but if something's leaking vacuum, then it's probably leaking boost under acceleration too. Which would mean you'd be running slightly rich..

About the passenger side inner fender thing.. When I got my TC, that hose was severed and just dangling in the fender. I just taped it off. From what I can tell, fordtech58 is right--the only thing I've noticed is that sometimes if I've been in boost for a while and switch climate control modes, I have to let off the gas to generate vacuum before it'll change the airflow.
88 TC 5-speed
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Pete D Offline
Administrator
#6
More: I pulled the codes. I got a 25 -KS - disconnected, 34 - EGR - been recalled, 74 - BOO - didn't hit the brake pedal, and a 41 - 02 - signal always lean. I expected that one.
Is it the 02 or is it due to the suspected vacuum leak? If it got contaminated with burning antifreeze, will it burn off? and how long would it take? I have put about 70 miles on it since it went together.

I've already run compression and fuel pressure checks and they were OK

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NATO Member. it's not a vice, it's an obsession
"The nice thing about each new day is nobody ever used it before" Barnaby Jones
88 TC X 2, 86 SVO, Main TC with K&N, 3"DP to 2.5"duals through Dynamax, Ric valve at 17+ and disconnected KS. Elite Bodega 16" chrome wheels. Autometer pod w/ A/F and Vac/boost gauges.140 mph Motorsports Speedo New engine: Total Seal rings and TRW pistons, ported and polished head w/ cc'd chambers,1.59"exhausts, SS valves, gutted upper, knife edged lower, A-230 cam, Race Engineering Adj Cam Sprocket, Crowlers, ARP head studs, and rod bolts. Walbro 255 HP pump and Kirban adj FPR, T-3. Centerforce II, KB subs and jack rails.
Pete Dunham


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segfaultxr7 Offline
Posting Freak
#7
From what I've read, antifreeze ruins whatever it is that reacts w/ oxygen in an O2 sensor. The sensor won't start working again once the antifreeze burns off, if it was contaminated in the first place.

I had a vacuum leak cause a Code 41 once. I had accidentally popped the PCV valve off. It would idle fine for a few seconds, then almost stall then come back up, with a check engine light & code 41. Do you get a light and/or any weird problems like that?
88 TC 5-speed
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Pete D Offline
Administrator
#8
Segfaultxr7, I get no check engine light. The car idles fine, given the cam, and it pulls fine, runs smooth.

I got another question. My view is that for a leak to affect vacuum readings, the leak has to be on the engine side of the throttle plate, in other words, in the TB, upper/lower intake, vacuum lines fed by the vacuum tree etc.
I know that a leak anywhere after the back of the VAM will affect A/F ratio. But, for example, a leak in an I/C hose will not cause a low vacuum reading
Anybody disagree? If so please explain the rational

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NATO Member. it's not a vice, it's an obsession
"The nice thing about each new day is nobody ever used it before" Barnaby Jones
88 TC X 2, 86 SVO, Main TC with K&N, 3"DP to 2.5"duals through Dynamax, Ric valve at 17+ and disconnected KS. Elite Bodega 16" chrome wheels. Autometer pod w/ A/F and Vac/boost gauges.140 mph Motorsports Speedo New engine: Total Seal rings and TRW pistons, ported and polished head w/ cc'd chambers,1.59"exhausts, SS valves, gutted upper, knife edged lower, A-230 cam, Race Engineering Adj Cam Sprocket, Crowlers, ARP head studs, and rod bolts. Walbro 255 HP pump and Kirban adj FPR, T-3. Centerforce II, KB subs and jack rails.
Pete Dunham


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TurboCougar Offline
Banned
#9
The whisteling sound is most likely the pcv valve, replace it and see if your problems go away. It is highly unlikely that teh oxygen sensor is related to a vacuum leak or whistleing noise but I would replace it anyway after working on the turbo as you did,they are important to keep fresh in these motors for peak performance and economy. Another thing you should check is the tube that plugs into the timed egr vacuum they are brittle when old and can crack easily causing a hard to find leak. Make sure the bolts on the egr valve are tight and that the valve is working properly and diaphragm not torn. Start with the PCV.
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Pete D Offline
Administrator
#10
Turbocougar. the PCV valve and related hoses are all (5K miles) new. I will check it though. I also have an additional one way check valve in the PCV line. All hose ends are clamped.
I agree that the 02 sensor is probably not related to the vacuum leak. It was working fine prior to pulling the turbo a couple months ago. I have some spares 02s (condition unknown) that I will cycle through it and if anything chnages then I'll get a new one.

The EGR vacuum system is fine. I have vacuum checked it. The valve is clean and tight and the gasket is good.

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NATO Member. it's not a vice, it's an obsession
"The nice thing about each new day is nobody ever used it before" Barnaby Jones
88 TC X 2, 86 SVO, Main TC with K&N, 3"DP to 2.5"duals through Dynamax, Ric valve at 17+ and disconnected KS. Elite Bodega 16" chrome wheels. Autometer pod w/ A/F and Vac/boost gauges.140 mph Motorsports Speedo New engine: Total Seal rings and TRW pistons, ported and polished head w/ cc'd chambers,1.59"exhausts, SS valves, gutted upper, knife edged lower, A-230 cam, Race Engineering Adj Cam Sprocket, Crowlers, ARP head studs, and rod bolts. Walbro 255 HP pump and Kirban adj FPR, T-3. Centerforce II, KB subs and jack rails.
Pete Dunham


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