1985 gt-s poor acceleration

Franken_Hachi
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1985 gt-s poor acceleration

Postby Franken_Hachi » Wed Dec 19, 2018 6:49 pm

So, I parked my car for the winter in 2009, in the spring it seemed to be running fine. I was having a spirited drive in May of the next year and it was running fine and all of a sudden it was bogging down from idle to around 4500rpm. I parked the car and kind of forgot about it for the 8 years. I decided to bring the car back from the dead this year and I started going through and replace seals and fluids. There were a few wired the mice had gotten at it. I tested the Maf and it tested out bad... Turns out my multimeter was bad. I took it for a drive tonight and it threw a code for a moment. A 6 and 11 when I got back to the garage. I just rebuilt the injectors, replaced all of the filters, plugs and wires, fuel pump the coil tested out just fine, the compression tested ok as well. It idles with a slight miss and stumbles when you rev it. I'm at a loss. I haven't touched the distributor and it happened when I took it out of storage. Any ideas? I was wondering if it jumped timing, but that would affect the compression, right?
1985 Corolla GT-S
2007 Camry (daily)
1994 Jeep Wrangler (lifted and stuff)
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jondee86
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Re: 1985 gt-s poor acceleration

Postby jondee86 » Wed Dec 19, 2018 8:22 pm

You should be able to do a quick cam timing check by pulling the top timing
belt cover. Turn the engine by hand until #1 cylinder is at TDC on the compression
stroke. Line the dimples on the cam pulleys with the marks on the backing plate.
Then look to see where the notch on the rim of the crank pulley is sitting. It should
be opposite the zero mark on the scale embossed on the lower timing belt cover.

Jumping a couple of teeth probably wouldn't have a big affect on compression
but it would retard your ignition timing by 10 deg, and that would take the edge
off your engine performance.

Cheers... jondee86
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Franken_Hachi
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Re: 1985 gt-s poor acceleration

Postby Franken_Hachi » Thu Dec 20, 2018 7:44 am

When I tested the throttle position sensor going between e2 and VTA it made no difference it was an open line no matter where I was in the spectrum.
1985 Corolla GT-S
2007 Camry (daily)
1994 Jeep Wrangler (lifted and stuff)
MECP Certified Installer
Insta: @franken_hachi

Franken_Hachi
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Re: 1985 gt-s poor acceleration

Postby Franken_Hachi » Thu Dec 20, 2018 10:09 am

Also the Maf tested @ 200 ohm closed, 600 open. The specs call for 20-3000 ohm. My only question is why was this thing running at all?
1985 Corolla GT-S
2007 Camry (daily)
1994 Jeep Wrangler (lifted and stuff)
MECP Certified Installer
Insta: @franken_hachi

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jondee86
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Re: 1985 gt-s poor acceleration

Postby jondee86 » Thu Dec 20, 2018 8:23 pm

AFAIK both those sensors have carbon ribbon potentiometers with a copper or brass
wiper. They probably got a bit of moisture inside from sitting outside so long. I never
tried this, but if you can open them up a spray with Electroclean (contact cleaner)
might help. EDIT: Just pulled a TPS apart and I can't say that I would recommend
trying to clean a TPS. Getting a new one off Ebay would be a better option.

The TPS is mainly used for acceleration enrichment. The engine will run without it
but better with a functioning unit. The AFM is the primary load input and controls
fueling. Based on my experience with the volume pots in old valve radios, the wiper
contact may improve with use.

Cheers... jondee86
Give a person a fish, they eat for a day. Suggest they search before posting, and they learn a skill for a lifetime.

totta crolla
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Re: 1985 gt-s poor acceleration

Postby totta crolla » Fri Dec 21, 2018 1:15 am

Distributor cap / rotor arm corrosion ?

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Re: 1985 gt-s poor acceleration

Postby Franken_Hachi » Fri Dec 21, 2018 3:58 am

The cap and rotor are new. I took the tps apart and there was a good amount of debris on the ribbon. The spring wasn't working well either. The same thing happened with the maf when I took it apart. I tested both circuit boards and they were testing out properly. The contact arm was making contact most of the time. Both peices were bad. I'm going to test the pick ups on the distributor next and confirm all of the solder joints are making connection. Thank you all for your help.
1985 Corolla GT-S
2007 Camry (daily)
1994 Jeep Wrangler (lifted and stuff)
MECP Certified Installer
Insta: @franken_hachi

totta crolla
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Re: 1985 gt-s poor acceleration

Postby totta crolla » Fri Dec 21, 2018 7:58 am

Last Year I bought my MR2 out of long term storage and it wouldn't start. The fuel pump was seized beyond repair. What a nice job fitting a new pump to that car....

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Re: 1985 gt-s poor acceleration

Postby Franken_Hachi » Fri Dec 21, 2018 1:41 pm

I had to replace the fuel pump in this one as well, at least they put in a convenient drain plug. long term storage is the worst. I parked it because of the way it was running and now I am tracking down that problem with more stacked on top. I'm about to go test the pick up coils and see if they spec out. Unfortunately I am going out of town for the holidays tomorrow, and this project is going on the back burner for a week. I spent quite a while working on the custom drive shaft, 8.8" rear diff swap, and the suspension, in retrospect I wish I would have worked on getting it running right first.
1985 Corolla GT-S
2007 Camry (daily)
1994 Jeep Wrangler (lifted and stuff)
MECP Certified Installer
Insta: @franken_hachi

Franken_Hachi
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Re: 1985 gt-s poor acceleration

Postby Franken_Hachi » Wed Dec 26, 2018 8:05 am

jondee86 wrote:AFAIK both those sensors have carbon ribbon potentiometers with a copper or brass
wiper. They probably got a bit of moisture inside from sitting outside so long. I never
tried this, but if you can open them up a spray with Electroclean (contact cleaner)
might help. EDIT: Just pulled a TPS apart and I can't say that I would recommend
trying to clean a TPS. Getting a new one off Ebay would be a better option.

The TPS is mainly used for acceleration enrichment. The engine will run without it
but better with a functioning unit. The AFM is the primary load input and controls
fueling. Based on my experience with the volume pots in old valve radios, the wiper
contact may improve with use.

Cheers... jondee86
you're 100% correct, they both have carbon ribbons.
1985 Corolla GT-S
2007 Camry (daily)
1994 Jeep Wrangler (lifted and stuff)
MECP Certified Installer
Insta: @franken_hachi

Franken_Hachi
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Joined: Thu Nov 08, 2018 5:54 pm

Re: 1985 gt-s poor acceleration

Postby Franken_Hachi » Sun Dec 30, 2018 2:20 pm

Image
Image
From what I can tell the timing marks are still on for both cam gears, I cannot see the marks on the crank very well but it seems to be idling fine. I pulled the dizzy cap and rotor, they both looked very worn out, I think I may have done a whole lot of things without checking the simple stuff first. The timing belt is chewed up and needs to be replaced.
Just to recap, the plugs, wires, tps, and maf have been replaced. all of those parts were replaced because they did not test to proper specifications. During the initial inspection I thought that the cap and rotor looked okay, but when I looked closer they were both trashed. They will be here Wednesday. Both pick ups in the distributor tested with in the tolerance. Compression was 165, 175, 175, 180. If the cap and rotor don't do the trick it's on the the ecu or ignitor. Thoughts and prayers. Edit: I didn't mention it, but I noticed the timing belt is destroyed. I forgot I rebuilt the injectors and replaced the fuel pump.
1985 Corolla GT-S
2007 Camry (daily)
1994 Jeep Wrangler (lifted and stuff)
MECP Certified Installer
Insta: @franken_hachi

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jondee86
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Re: 1985 gt-s poor acceleration

Postby jondee86 » Sun Dec 30, 2018 3:57 pm

Was the timing belt loose/slack when you checked ? If the belt is going to jump teeth
it will be more likely to do that on the crank sprocket. And if that is the case the marks
on the cam sprockets can look good but the mark on the crank pulley will be out.

Anyway, you are going to have to pull the radiator and the crank pulley to change the
timing belt. So you will be able to freshen up the timing marks and check the ignition
timing while you are in there.

Cheers... jondee86
Give a person a fish, they eat for a day. Suggest they search before posting, and they learn a skill for a lifetime.

Franken_Hachi
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Re: 1985 gt-s poor acceleration

Postby Franken_Hachi » Sun Dec 30, 2018 5:35 pm

I went and checked the belt, and there was too much deflection. When the symptoms started I was just below red line, so it very likely jumped timing. One question, what are the sensors on the front left of the block? Mine is gunked up so bad I just spotted them. Other than the water pump and tensioner while I'm in the front of the engine?
1985 Corolla GT-S
2007 Camry (daily)
1994 Jeep Wrangler (lifted and stuff)
MECP Certified Installer
Insta: @franken_hachi

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jondee86
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Re: 1985 gt-s poor acceleration

Postby jondee86 » Sun Dec 30, 2018 9:55 pm

I'm not schooled up on USDM cars... but I'm pretty sure that there are two water
temp sensors on the water neck that comes from the head to the radiator. A single
wire sensor for the dash gauge and a two wire sensor (green) for the ECU. There
could be more but someone else will need to clarify that.

If the engine hasn't been rebuilt before, it would be a good idea to replace the cam
seals and the crankshaft front seal while you have the covers off.

Cheers... jondee86
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oldeskewltoy
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Re: 1985 gt-s poor acceleration

Postby oldeskewltoy » Mon Dec 31, 2018 8:25 am

hmmmm, compression wouldn't be very good, nor would it idle smoothly if the belt had actually slipped.

The belt does look loose.... 2nd panel down is the spec: 2 kilos - 4mm deflection between the cams...

Image
OST Cyl head porting, - viewtopic.php?f=22&t=300

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Re: 1985 gt-s poor acceleration

Postby totta crolla » Mon Dec 31, 2018 9:20 am

Deleted ;)
Last edited by totta crolla on Tue Jan 01, 2019 5:33 am, edited 1 time in total.

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Re: 1985 gt-s poor acceleration

Postby Franken_Hachi » Mon Dec 31, 2018 3:18 pm

totta crolla wrote:What a bullshit waste of time this is...
So the distributor cap and rotor arm go from being new to very worn out....

I can assure you I did not go out of my way to deceive you. If you keep it up I'm going to kiss you on the mouth. I replaced the wires and plugs on the hachi, and the wires, plugs rotor and cap on my jeep. I'm not usually in the business of explaining myself, but you should consider saying your sorry. a wise man once said.
Craig Benzine wrote:Based on this one experience I had, jumping to conclusions is always really stupid.


now that I've fed the troll, back to the hatch. Last night I ordered the cap, rotor, water pump, timing belt, and idler pulley. I'm glad I have the next 4 months to work through this old girl. Autocross season is right around the corner.
Image
Image
Image
oldeskewltoy wrote:hmmmm, compression wouldn't be very good, nor would it idle smoothly if the belt had actually slipped.

The belt does look loose.... 2nd panel down is the spec: 2 kilos - 4mm deflection between the cams...

thats what I was thinking, but I have never had a vehicle jump just a few teeth. the last time I had a timing belt go bad It destroyed the head on my crx. pesky interference engines. Thank you for the diagrams those are going to be super helpful when the parts get here.
1985 Corolla GT-S
2007 Camry (daily)
1994 Jeep Wrangler (lifted and stuff)
MECP Certified Installer
Insta: @franken_hachi

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jondee86
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Re: 1985 gt-s poor acceleration

Postby jondee86 » Mon Dec 31, 2018 3:52 pm

Image

The timing belt may or may not have jumped a couple of teeth. But the fact that
the performance of the engine changed suddenly does make it a possibility that you
need to eliminate. Replacing worn parts eliminates them as contributing factors.

Nothing wrong here... move along :)

Cheers... jondee86
Give a person a fish, they eat for a day. Suggest they search before posting, and they learn a skill for a lifetime.

totta crolla
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Re: 1985 gt-s poor acceleration

Postby totta crolla » Tue Jan 01, 2019 2:41 am

It was the dismissive one liner "the cap and rotor are new".... move on fool, it's not that. Do you think I'm stupid ? type of comment that got my goat.
A wiser man once said "dismiss the obvious at your peril"
Happy New Year ! x

Franken_Hachi
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Re: 1985 gt-s poor acceleration

Postby Franken_Hachi » Tue Jan 01, 2019 4:42 am

Sorry, I got a little snappy. I just burried my mother, happy new year. Trust me, the confusion is real.
1985 Corolla GT-S
2007 Camry (daily)
1994 Jeep Wrangler (lifted and stuff)
MECP Certified Installer
Insta: @franken_hachi

totta crolla
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Re: 1985 gt-s poor acceleration

Postby totta crolla » Tue Jan 01, 2019 5:28 am

Hey no problem, been there, done that and I know your pain.
It gets a little easier with time.
Maybe a few Hachi problems will take your mind off things for a while ?
Deleted my post.

Franken_Hachi
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Re: 1985 gt-s poor acceleration

Postby Franken_Hachi » Fri Jan 04, 2019 1:50 pm

She's putting in work, I found one more broken wire and I replace the cap and rotor made sure that all my grounds are good and fired her up again. She is running pretty good, now I have to get the timing belt changed and the exhaust sorted out.
1985 Corolla GT-S
2007 Camry (daily)
1994 Jeep Wrangler (lifted and stuff)
MECP Certified Installer
Insta: @franken_hachi

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