88 Supra - Problem Holding Idle

[alexdeschutter]

I went to look at an 1988 supra(automatic) today.
No turbo, and was completely stock as far as i could tell.
The price is fairly low, it runs and starts but i didnt get to drive it.
In the driveway where I started it, i shifted from Park to Reverse to Drive and back a couple of times.
It would run alright but i had to give keep my foot on the pedal otherwise it would slowly begin to stall as the RPMs dropped.
I would like to purchase this vehicle and will be going back with a mechanic(ally inclined friend) for further inspection (check for BHGS and possibly do a compression test).

Does it fall out of idle because of the MAF?
THX for reading and any wisdom you can impart!

[Bill UK]

Could be just the throttle positioning sensor needs adjusting, the main problem is BHG and big ends. (Apart from rusty rear wheel arches)
You can download the Toyota work shop manual from Here or use the cygnusx1 on line. Big ends you will hear at cold start up and 2k to 3k revs. BHG; check the coolant expansion bottle after a 30 mile hard drive, you should see the coolant rise no more than an inch, if that. The best way is to do a sniff test or compression test. Also listen for any gurgling sound behind the dash at cold start up.

[alexdeschutter]

Originally Posted by Bill UK

Could be just the throttle positioning sensor needs adjusting, the main problem is BHG and big ends. (Apart from rusty rear wheel arches)
You can download the Toyota work shop manual from Here or use the cygnusx1 on line. Big ends you will hear at cold start up and 2k to 3k revs. BHG; check the coolant expansion bottle after a 30 mile hard drive, you should see the coolant rise no more than an inch, if that. The best way is to do a sniff test or compression test. Also listen for any gurgling sound behind the dash at cold start up.

i will be sure to lowball this guy if there is a BHG, because ive heard those are pricey/timely to fix. Anyone have a good estimate on how much time/money it would take to do a BHG repair?
whats the big ends you are talking about?

[alexdeschutter]

i will be sure to lowball this guy if there is a BHG, because ive heard those are pricey/timely to fix.
i think i can manage to run a compression test, if i can find the equipment and the current owner will let me.


Anyone have a good estimate on how much time/money it would take to do a BHG repair?
and
What is the Big Ends issue that you mentioned? Could you please elaborate on what it is?

[Bill UK]

Check this out for Big Ends Link .Head gasket replacement around GBP 400 -GBP 500 for parts including head refurbishment. Probably GBP 1500 + if you let a garage do it. Will fill in the detail later as soon as I return from work.

[alexdeschutter]

Originally Posted by Bill UK

Check this out for Big Ends Link .Head gasket replacement around GBP 400 -GBP 500 for parts including head refurbishment. Probably GBP 1500 + if you let a garage do it. Will fill in the detail later as soon as I return from work.

I checked out the Big Ends link, and was curious if there is anyway to make sure this 88 Supra doesnt have that problem, before i buy it. I plan on taking it for a test drive... What should i look for?

It sounds like the labour of changing a BHG would be the priciest part. I think my friend and I could change the HG though, but not refurbish the head.
Awaiting the details man! Any knowledge you have about either topic is extremely valued!

[bills1988]

My 88 has 130K miles and recently began to drop idle speed "intermittently". Would usually start fine and the idle would drift down from about 1200 to the spec 800 (this is normal). It seems after driving and warming up to operating temp, and when I pull up to a stop light, the idle will sometimes (not always) drop to about 400-600 rpm. It usually recovers, but not always. Like I said, it is intermittent. The Toyota dealer/mechanic said it was probably the ISC Valve (Idle Speed Control Valve) which he called a Idle Stepper Motor. He said it may have some mechanical shaft wear causing the problem. This is an easy part to replace, but it is an expensive part (about $400+ online). I plan to continue monitoring it and seeing if I can live with it or at least determine the exact conditions when it happens. Here is the procedure (there are two pages, 106 & 107) for checking out the ISC:
http://www.cygnusx1.net/Supra/Librar...spx?S=FI&P=106

Hope this helps.

[alexdeschutter]

mine doesnt idle low, it will just idle lower and lower until it stalls. Possibly the same problem?

[Makz]

The first thing you shuld do - is to run self-diagnostic systems and read errors on ECU. It's very simple to do. TRSM will help you.
It may be ISCV, MAF, TPS, throttle itself, holes in intake or vacuum pipes and so on...too many things...

[Bill UK]

Originally Posted by alexdeschutter

I checked out the Big Ends link, and was curious if there is anyway to make sure this 88 Supra doesnt have that problem, before i buy it. I plan on taking it for a test drive... What should i look for?

It sounds like the labour of changing a BHG would be the priciest part. I think my friend and I could change the HG though, but not refurbish the head.
Awaiting the details man! Any knowledge you have about either topic is extremely valued!

This will give you some idea of the cost of a BHG repair, depending on how bad the head surface is, you could get away with just cleaning it up yourself, providing its flat enough. As I went to all the trouble or removing it, I decided to have it refurbished. Gaskets are around GBP 100. Toyota head bolts are GBP 8 each or ARP studs/bolts GBP 100 per set. As you can see it soon mounts up. A lot more info HERE. The pound sign doesn’t work on the form so I've used GBP instead, the dollar $ sign is ok though. Surrey in the UK I assume.
The prices in the invoice should be about the same today.