I rebuilt the 7MGE in this Cressida about 1200 miles ago, it was
running like a clock this morning. I fired it up tonight and it
displayed a severe miss.

I'm getting spark from all distributor contacts to the wires,
confirmed by pulling them out one at a time while the engine was
running.

Results of a compression test after it sat for about an hour

1 180
2 175
3 160
4 189
5 160
6 195


I put it back together and fired it up to get it up to operating temp
again and did it again immediately. During this warm up, I noticed the
miss was still there but less pronounced than it had been previously.


1 200
2 180
3 170
4 180
5 170
6 195

All the cylinders came up somewhat, some more than others. The shop
manual lists 120 psi as the low minimum, obviously they're all over
that.

I squired some oil in the two low cylinders 3 & 5, 3 came up to 180, 5
came up to 200. Just for grins I put oil in the #1 cylinder, which was
the high of the second test, it went to 210.

I'm a bit concerned about what appears to be a fairly wide gap between
the lowest and highest cylinders. Is this normal for 1200 miles out
from a rebuild? Also, wondering about how some of the cyls increased
up more than others when checked hot. The miss I was experiencing was
as if one of the cylinders had flat quit - running rough and an
obvious *pap pap pap* at the exhaust pipe where it's normally a quite,
silky whoosh. Do any of these cyl pressure differences seem to be
enough to cause this?

It's a new engine, hasn't overheated, the lowest cyls aren't adjacent
and it isn't losing any water so it would seem a head gasket isn't
indicated. It certainly didn't blow a gasket sitting there in the
parking lot.

Not burning any oil as far as I can tell. I did the first oil change
at around 1000 miles and it's still quite clear on the dipstick after
200 - 300 miles since changing. The plugs aren't new but they look
okay, none of the electrodes are fried.

Ran like a Swiss watch this morning and ever since the rebuild. Fired
it up, and now it's got a problem. <scratch head>

It seems like something that could go bad quick. Maybe an injector?
Any definitive way to check with them installed?

Other theories?

Thanks for all input.

i think those are good compression numbers. all are over 150. there is
only about 15% difference between the lowest and highest.

"Doc" <docsavage20@yahoo.com> wrote in message
news:c8cfcad1-e80a-408d-9d92-112f50868e47@b40g2000prf.googlegroups.com...
>I rebuilt the 7MGE in this Cressida about 1200 miles ago, it was
> running like a clock this morning. I fired it up tonight and it
> displayed a severe miss.

Does it have hydraulic or adjustable tappets? Could well be a tight valve
that's bedding in and closed up the gap, causing the valve to leak. This
would explain the change when the engine temp varies.

Check all the usual other suspects like injectors, injector seals on the
intake and air leaks somewhere.

SD

"Doc" <docsavage20@yahoo.com> wrote in
message
news:c8cfcad1-e80a-408d-9d92-112f50868e47@b40g2000prf.googlegroups.com...
>I rebuilt the 7MGE in this Cressida
>about 1200 miles ago, it was
> running like a clock this morning. I
> fired it up tonight and it
> displayed a severe miss.
>
> I'm getting spark from all distributor
> contacts to the wires,
> confirmed by pulling them out one at a
> time while the engine was
> running.
>
> Results of a compression test after it
> sat for about an hour
>
> 1 180
> 2 175
> 3 160
> 4 189
> 5 160
> 6 195
>
>
> I put it back together and fired it up
> to get it up to operating temp
> again and did it again immediately.
> During this warm up, I noticed the
> miss was still there but less
> pronounced than it had been
> previously.
>
>
> 1 200
> 2 180
> 3 170
> 4 180
> 5 170
> 6 195
>
> All the cylinders came up somewhat,
> some more than others. The shop
> manual lists 120 psi as the low
> minimum, obviously they're all over
> that.
>
> I squired some oil in the two low
> cylinders 3 & 5, 3 came up to 180, 5
> came up to 200. Just for grins I put
> oil in the #1 cylinder, which was
> the high of the second test, it went
> to 210.
>
> I'm a bit concerned about what appears
> to be a fairly wide gap between
> the lowest and highest cylinders. Is
> this normal for 1200 miles out
> from a rebuild? Also, wondering about
> how some of the cyls increased
> up more than others when checked hot.
> The miss I was experiencing was
> as if one of the cylinders had flat
> quit - running rough and an
> obvious *pap pap pap* at the exhaust
> pipe where it's normally a quite,
> silky whoosh. Do any of these cyl
> pressure differences seem to be
> enough to cause this?
>
> It's a new engine, hasn't overheated,
> the lowest cyls aren't adjacent
> and it isn't losing any water so it
> would seem a head gasket isn't
> indicated. It certainly didn't blow a
> gasket sitting there in the
> parking lot.
>
> Not burning any oil as far as I can
> tell. I did the first oil change
> at around 1000 miles and it's still
> quite clear on the dipstick after
> 200 - 300 miles since changing. The
> plugs aren't new but they look
> okay, none of the electrodes are
> fried.
>
> Ran like a Swiss watch this morning
> and ever since the rebuild. Fired
> it up, and now it's got a problem.
> <scratch head>
>
> It seems like something that could go
> bad quick. Maybe an injector?
> Any definitive way to check with them
> installed?
>
> Other theories?
>
> Thanks for all input.



I don't think your compression is a
problem. Or your gauge is very accurate.
If you need the numbers my TSRM shows
the warm engine pressure @ 156 psi. The
minimum is 128 and the difference
between each cylinder less than 14 psi.

When you put it back together and the
problem changed that is a big clue. I
would assume you checked the OBD
diagnostic output is "normal" right!
Check the engine air intake pipes and
vacuum hoses for leaks. The one from the
intake pipe to the power steering is
real easy to miss for example.
Check the spark plug wires with a ohm
meter. Measure from the terminal inside
the distributor cap to the end of each
wire. Maximum resistance is 25 ohms.

I would check the coil wire and for
intake leaks before the throttle body
first.

GL
Dan

"Doc" <docsavage20@yahoo.com> wrote in
message
news:a6bd6bbb-7240-49c5-b9a9-712a11dcc8b5@o6g2000hsd.googlegroups.com...
> On Dec 10, 7:13 am, "Stewart DIBBS"
> <s...@pixcl.com> wrote:
>
>> >I rebuilt the 7MGE in this Cressida
>> >about 1200 miles ago, it was
>> > running like a clock this morning.
>> > I fired it up tonight and it
>> > displayed a severe miss.
>>
>> Does it have hydraulic or adjustable
>> tappets? Could well be a tight valve
>> that's bedding in and closed up the
>> gap, causing the valve to leak. This
>> would explain the change when the
>> engine temp varies.
>
>
> After putting everything back together
> again, the problem has
> disappeared. Running silky smooth
> again...hmmm
>
> Wondering if maybe a spark plug boot
> that wasn't quite snapped on
> tight lifted off. The point at which
> the boots snap into the cover and
> the contacts snap onto the plugs is
> pretty much the same, maybe
> causing some upward tension.


In the past I have found my #1 wire like
that after working on the engine. And
then forgetting to reconnect the plug
wire when done. But the engine ran fine
so I doubt it.

A word of warning though. If that center
cover (head cover #3) the wires go thru
is not water tight do not let water gets
in there. The #2 and #3 plug valleys
will never dry out (even if it boils)
and their burried under the intake.

>
> Re: the lifters, it's a DOHC, I was
> under the impression they're
> hydraulic however I know they're
> adjustable by way of shims and the
> shop manual has procedures to check
> and replace them. It's had a
> couple of head rebuilds since the car
> was new but I don't know for a
> fact whether this was checked. I think
> it might be worth doing anyway
> since the car has over 130k on it.


Could have sworn someone said "I rebuilt
the 7MGE in this Cressida about 1200
miles ago"!!!!!!! 8)


> Thanks for the suggestions.

On Mon, 10 Dec 2007 11:00:23 -0800, Danny G. wrote:

>> and replace them. It's had a
>> couple of head rebuilds since the car was new but I don't know for a
>> fact whether this was checked. I think it might be worth doing anyway
>> since the car has over 130k on it.
>
>
> Could have sworn someone said "I rebuilt the 7MGE in this Cressida about
> 1200
> miles ago"!!!!!!! 8)


130K and a *COUPLE* of head rebuilds?!?!

Whew! My Supra has 200+ and hasn't had a head rebuild yet!

You must *REALLY* like this car!

On Mon, 10 Dec 2007 04:29:44 -0800 (PST), Doc <docsavage20@yahoo.com>
wrote:

>On Dec 10, 7:13 am, "Stewart DIBBS" <s...@pixcl.com> wrote:
>
>> >I rebuilt the 7MGE in this Cressida about 1200 miles ago, it was
>> > running like a clock this morning. I fired it up tonight and it
>> > displayed a severe miss.
>>
>> Does it have hydraulic or adjustable tappets? Could well be a tight valve
>> that's bedding in and closed up the gap, causing the valve to leak. This
>> would explain the change when the engine temp varies.
>
>
>After putting everything back together again, the problem has
>disappeared. Running silky smooth again...hmmm



>Wondering if maybe a spark plug boot that wasn't quite snapped on
>tight lifted off. The point at which the boots snap into the cover and
>the contacts snap onto the plugs is pretty much the same, maybe
>causing some upward tension.

If you're not feeling a slight click when you push in the plug wire,
replace your wires.


>
>Re: the lifters, it's a DOHC, I was under the impression they're
>hydraulic however I know they're adjustable by way of shims and the
>shop manual has procedures to check and replace them. It's had a
>couple of head rebuilds since the car was new but I don't know for a
>fact whether this was checked. I think it might be worth doing anyway
>since the car has over 130k on it.


COUPLE? If that's true, you'd be better off just replacing the 7MGE.
Surely you know a used one with under 40K can be had for less than you
can buy one at a local junkyard? Google. Be amazed.
--
gburnore at DataBasix dot Com
---------------------------------------------------------------------------
How you look depends on where you go.
---------------------------------------------------------------------------
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| ÝÛ 0 1 7 2 3 / Ý³Þ 3 7 4 9 3 0 Û³
Black Helicopter Repair Services, Ltd.| Official Proof of Purchase
================================================== =========================

"Doc" <docsavage20@yahoo.com> wrote in message
news:c8cfcad1-e80a-408d-9d92-112f50868e47@b40g2000prf.googlegroups.com...
>I rebuilt the 7MGE in this Cressida about 1200 miles ago, it was
> running like a clock this morning. I fired it up tonight and it
> displayed a severe miss.
>
> I'm getting spark from all distributor contacts to the wires,
> confirmed by pulling them out one at a time while the engine was
> running.
>
> Results of a compression test after it sat for about an hour
>
> 1 180
> 2 175
> 3 160
> 4 189
> 5 160
> 6 195
>
>
> I put it back together and fired it up to get it up to operating temp
> again and did it again immediately. During this warm up, I noticed the
> miss was still there but less pronounced than it had been previously.
>
>
> 1 200
> 2 180
> 3 170
> 4 180
> 5 170
> 6 195
>
> All the cylinders came up somewhat, some more than others. The shop
> manual lists 120 psi as the low minimum, obviously they're all over
> that.
>
> I squired some oil in the two low cylinders 3 & 5, 3 came up to 180, 5
> came up to 200. Just for grins I put oil in the #1 cylinder, which was
> the high of the second test, it went to 210.
>
> I'm a bit concerned about what appears to be a fairly wide gap between
> the lowest and highest cylinders. Is this normal for 1200 miles out
> from a rebuild? Also, wondering about how some of the cyls increased
> up more than others when checked hot. The miss I was experiencing was
> as if one of the cylinders had flat quit - running rough and an
> obvious *pap pap pap* at the exhaust pipe where it's normally a quite,
> silky whoosh. Do any of these cyl pressure differences seem to be
> enough to cause this?
>
> It's a new engine, hasn't overheated, the lowest cyls aren't adjacent
> and it isn't losing any water so it would seem a head gasket isn't
> indicated. It certainly didn't blow a gasket sitting there in the
> parking lot.
>
> Not burning any oil as far as I can tell. I did the first oil change
> at around 1000 miles and it's still quite clear on the dipstick after
> 200 - 300 miles since changing. The plugs aren't new but they look
> okay, none of the electrodes are fried.
>
> Ran like a Swiss watch this morning and ever since the rebuild. Fired
> it up, and now it's got a problem. <scratch head>
>
> It seems like something that could go bad quick. Maybe an injector?
> Any definitive way to check with them installed?
>
> Other theories?
>
> Thanks for all input.


Me thinks your motor is not well.

You are way above the min. spec, but you have a very wide difference between
the high and low pistons, and they are adjacent to one another. I seem to
recall the spread should not exceed 10% -- your high pressure is 200, the
weakest one should be at least 180. Your weakest cylinder is nearly 20%
below the strongest one. That can't be good.

Except that the spread is almost 20%. The highest is 195, the lowest is 160.
This difference is 35. 19 is 10% of the highest reading, and 38 would be 20%
of the highest.

The spread from highest to lowest is closer to 20% than 15%.




<boxing@sasktel.net> wrote in message
news:320ef111-69d9-441c-a2f3-6d5886f2c1b9@t1g2000pra.googlegroups.com...
>i think those are good compression numbers. all are over 150. there is
> only about 15% difference between the lowest and highest.

On Tue, 11 Dec 2007 00:11:09 GMT, "Jeff Strickland"
<crwlr@verizon.net> wrote:

>
>"Doc" <docsavage20@yahoo.com> wrote in message
>news:c8cfcad1-e80a-408d-9d92-112f50868e47@b40g2000prf.googlegroups.com...
>>I rebuilt the 7MGE in this Cressida about 1200 miles ago, it was
>> running like a clock this morning. I fired it up tonight and it
>> displayed a severe miss.
>>
>> I'm getting spark from all distributor contacts to the wires,
>> confirmed by pulling them out one at a time while the engine was
>> running.
>>
>> Results of a compression test after it sat for about an hour
>>
>> 1 180
>> 2 175
>> 3 160
>> 4 189
>> 5 160
>> 6 195
>>
>>
>> I put it back together and fired it up to get it up to operating temp
>> again and did it again immediately. During this warm up, I noticed the
>> miss was still there but less pronounced than it had been previously.
>>
>>
>> 1 200
>> 2 180
>> 3 170
>> 4 180
>> 5 170
>> 6 195
>>
>> All the cylinders came up somewhat, some more than others. The shop
>> manual lists 120 psi as the low minimum, obviously they're all over
>> that.
>>
>> I squired some oil in the two low cylinders 3 & 5, 3 came up to 180, 5
>> came up to 200. Just for grins I put oil in the #1 cylinder, which was
>> the high of the second test, it went to 210.
>>
>> I'm a bit concerned about what appears to be a fairly wide gap between
>> the lowest and highest cylinders. Is this normal for 1200 miles out
>> from a rebuild? Also, wondering about how some of the cyls increased
>> up more than others when checked hot. The miss I was experiencing was
>> as if one of the cylinders had flat quit - running rough and an
>> obvious *pap pap pap* at the exhaust pipe where it's normally a quite,
>> silky whoosh. Do any of these cyl pressure differences seem to be
>> enough to cause this?
>>
>> It's a new engine, hasn't overheated, the lowest cyls aren't adjacent
>> and it isn't losing any water so it would seem a head gasket isn't
>> indicated. It certainly didn't blow a gasket sitting there in the
>> parking lot.
>>
>> Not burning any oil as far as I can tell. I did the first oil change
>> at around 1000 miles and it's still quite clear on the dipstick after
>> 200 - 300 miles since changing. The plugs aren't new but they look
>> okay, none of the electrodes are fried.
>>
>> Ran like a Swiss watch this morning and ever since the rebuild. Fired
>> it up, and now it's got a problem. <scratch head>
>>
>> It seems like something that could go bad quick. Maybe an injector?
>> Any definitive way to check with them installed?
>>
>> Other theories?
>>
>> Thanks for all input.
>
>
>Me thinks your motor is not well.
>
>You are way above the min. spec, but you have a very wide difference between
>the high and low pistons, and they are adjacent to one another. I seem to
>recall the spread should not exceed 10% -- your high pressure is 200, the
>weakest one should be at least 180. Your weakest cylinder is nearly 20%
>below the strongest one. That can't be good.
>

From the 7MGE Manual:
The engine must be warm when performing the test.
The test must be performed as quickly as possible. Meaning
waiting between testing of each cyl can slew the results.


Std Pressure: 156PSI or more.
Min Pressure: 128PSI

The important part:

Difference between cyl: 14PSI

So using his second test:

1 - 2 Diff 20 Bad
2 - 3 Diff 10 Ok
3 - 4 Diff 10 Ok
4 - 5 Diff 10 Ok
5 - 6 Diff 15 Barely Bad.


Since adding oil to each cyl caused the test to go up fairly
uniformly, it's likely that the rings are shot.



--
gburnore at DataBasix dot Com
---------------------------------------------------------------------------
How you look depends on where you go.
---------------------------------------------------------------------------
Gary L. Burnore | ÝÛ³ºÝ³Þ³ºÝ³³Ýۺݳ޳ºÝ³Ý³Þ³ºÝ³ÝÝÛ³
| ÝÛ³ºÝ³Þ³ºÝ³³Ýۺݳ޳ºÝ³Ý³Þ³ºÝ³ÝÝÛ³
Official .sig, Accept no substitutes. | ÝÛ³ºÝ³Þ³ºÝ³³Ýۺݳ޳ºÝ³Ý³Þ³ºÝ³ÝÝÛ³
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================================================== =========================