five7kid

iTrader: (14)

Vehicle is a '91 Pontiac Bonneville, 3800, ~115k. Last summer, was loosing power when warm, replaced fuel pump & filter - that problem went away. But, started to become harder and harder to start, especially as winter arrived. Have always noted that there is no residual pressure on fuel system, and plugs were dry when it wouldn't start, so replaced FPR - still hard to start, but now plugs are wet. Replace plugs & wires in December, easier to start but still a bear. Have to floor it to keep it from flooding. But, once it catches, it idles great, has good power, will run right up to the redline, gas mileage is fine (I keep track of it each fillup). Doesn't matter if cold or warm, never fires off right away (only floods when cold, though - usually starts 3rd try when warm).

Finally Sunday, on way home from Superbowl party in a snowstorm, SES light comes on, stayed on through yesterday. Checked codes, 63: scanner book gives 4 possibilities, including MAP sensor which it doesn't have; Haynes says "ERG flow". Ran Auto Xray (thanks, Gary @ Checker), no current codes, 63 in memory, "EGR Solenoid 3". (Dealer service department says "Requires technician - bring it in.")

Could an EGR valve cause hard starting but not running problems? Replacement is $275 (!). I've picked up a new O2 sensor, but doubt that could cause cold start problems (or even hot start, for that matter).

Sorry for long post, this has been a nagging problem. I've had 3 (including this one) high-mileage Bonnevilles, '89-91, this is the only one that has had this problem. Daughters love the car (since they can't have the Camaro), shotgun has been considered but that option rejected.

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82 Berlinetta, orig V-6 car, now w/86 LG4/TH700R. 2.93 limited slip. Cat-back from '91 GTA, Accel HEI SuperCoil. AMSOIL syn lubes bumper-to-bumper. Daily driver, work-in-progress (LG4 w/LB9 block, ZZ3 cam and intake, WP 305 heads ported & polished, Hooker headers & y-pipe, hi-flow cat).
57 Bel Air, my 1st car. 0.030 over 396, Weiand Action+, Edelbrock 1901 Q-Jet, Jacobs Omnipack, 1-3/4" headers, TH400 w/TCI Sat Night Special conv & shift kit, 3.08 10-bolt, AMSOIL syn lubes bumper-to-bumper. Best 15.1 @ 5800' Bandimere. Daily driver while Camaro was being put together.

8Mike9

::Could an EGR valve cause hard starting but not running problems? ::

Yes it could. EGR at idle can cause no start, hard start and poor idle,and once you put you foot in to it, she'll run fine.

But you say once it fires up, she idles fine, so I'd hold off on the EGR...my feeling is if it was causing hard starts, the idle would be choppy as well.

Might want to look at the CTS, it probably provides a lot of start up info, cold or hot, should ohm out the same as our cars do, monitor the resistance at startup and compare, Haynes should have a table in it to compare temp vs. resistance.

O2 shouldn't be used for startup on this car.

Have you cleaned the TB and IAC yet?

five7kid

iTrader: (14)

I suspect the EGR code was intermittent, and not related to the cold start problem (didn't throw the code at startup, but while driving that night). I'm holding off on replacement for sure.

I have not looked at the CTS, but plan on purchasing that scanner tomorrow morning. While using the borrowed one, I thought it said 210.2 or something like that when I had the engine shut off but had been idling. The temp gage did not indicate that hot, but like Vader says, don't trust it. I'm a little puzzled how the CTS would cause this problem, but obviously don't fully understand what all it affects.

I did clean the TB, didn't make any difference. I haven't done anything with the IAC, but Vader's post on the other cold start post will help me through that.

Thanks for the response. I plan on doing more when I have the scanner to play with. Will post any findings.

In case anyone's miffed that this is non-3rd gen, it's my parts runner when I'm working on the Camaro

ede

just a WAG but how about the FPR? is it leaking off? i'm thinking your code is unrelated to you problem, or maybe caused by your problem and may go away when you get it fixed.

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ICON Motorsports

1st & 3rd

ede

thought about this a little more, what's the chance you have a bad fuel pump? i've bought other new parts before that didn't work, or failed not long after they were installed. have you had any of the lines off and damaged a o ring (thats a long shot i think).
i also recall gm have a no intermitent no start problem on the mid to late 80 cars but i can't remember what it was. i'd try e mailing one or several of the gm techs that come here and asking.

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ICON Motorsports

1st & 3rd

five7kid

iTrader: (14)

I seriously considered the bad fuel pump idea when I had no residual fuel pressure and the plugs were dry after some serious cranking. But, since replacing the fuel pressure reg, flooding after short cranking has been the norm (the day I replaced the plugs, they were still wet 4 hours after I last cranked it). I don't have a fuel pressure gage, but on one occasion I depressed the Schrader valve while the pump was still running but the engine wasn't, and I got Old Faithful.

It would seem that it is something related to a start-only circuit. I don't know what "start-only" circuits exist (there are a lot of wires going to the coil pack, for instance). ECM?

I'll take your advice about the techs. In the meantime, if anyone has any ideas...

five7kid

iTrader: (14)

Ran the AutoXray this morning before the car was started. Results:

Scan before started, no current trouble codes, 63 still in history.

Monitor w/key on, engine not turned over. CTS read 46.4 degrees, air inlet 41.6 (both close to outside temp.). A couple of curious things noted were "Engine Hot Light - On", "Hi Altitude Air - No", "IAC Learned - No", "Learn Control Disabled". I don't know exactly what they should be saying, but, for instance, I'm at 5800' altitude: What's considered "Hi Altitude"?

Started the car, hard to do as usual, then these things noted: engine hot light went to off; hi altitude still no; went to closed loop in about 4 minutes of idling; IAC Learned stayed "No"; things seemed to be responding in what seemed reasonable ways. Idle air mtr changed position as idle decreased w/increased engine temp. I think Learn Control went to enable, but can't remember for sure now. Throttle and O2 sensor voltages changed with throttle/engine speed. Rich Lean flag toggled between rich & lean. CCP duty cycle stayed at 0.0% throughout (not sure exactly what that is). There were things called "QDM" with a number behind it, not sure what that is, either, but I believe they all said "low".

Not sure if there are any clues in there. Any more ideas?

[This message has been edited by five7kid (edited February 03, 2001).]

Engineboy

Whats TPS voltage??

five7kid

iTrader: (14)

At idle, it's 0.39 volts. I saw it go up to over two when I gunned it, but I haven't done a full-range check without the engine running. Do you need that data?

Engineboy

I would try setting the TPS to a little above .5v at idle.

It should sweep (with the engine off ) to about 4.5 volts at WOT.

what is CTS temp when cold??

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ASE Mechanic/Machinist/Smog Tech

1999 NBM Trans Am
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[This message has been edited by Engineboy (edited February 03, 2001).]

82 TRANS AM

57kid, Is your coil pack original? When they go bad (3 packs of 2) they take over for each other weakening your whole spark in general. Old wires and spark plugs take their toll on them. You said the light came on at night. Just a thought. My driver is a 3800 ('90 Olds Toronado Trofeo) with 125k. The only problem i've ever had is the crank trigger went bad. FYI If the car won't start hot but cools off and starts, that's what it is.
3800's kick gas

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Kenney
82 Trans Am WS7 notchback
83 Trans Am WS6 T-tops
72 Vista Cruiser 455
90 Olds Trofeo
80 K-10 w/snow plow
Painter @ Chevy dealer
GM junkie

five7kid

iTrader: (14)

Engineboy, the CTS temp when cold said 46 degrees, which was 5 degrees off from the air temp at the time. I believe it is okay. I could try adjusting the TPS as you suggest, though.

82 Trans, I've wondered about that coil pack, and yes, as far as I know it's original. That is one thing that seems to fit with most everything else. I've also considered the crank trigger, but the condition you described does not fit (know of a GN that had the trigger go bad, he got an SES light - also ran poorly when warmed up).

I've got a source for a coil pack. I think I'll give it a try (could also try switching it with my other Bonneville). Why can't the computer monitor it????

Thanks for all the input. I'll let you know. Unless someone else knows what it is...

Guest

IIRC the coil pack has its own controller module, which is separate from the ECM itself. It does kinda sound like a bad coil pack though. My only other curiousity (since I just ran into stupid battery problems recently) is whats the battery voltage when you try to start it?

five7kid

iTrader: (14)

Hummm, good question. I didn't monitor that during cranking. It was 12.0 before starting, and 14.3 while running.

I did on one occasion have it jumped while trying to get it to start - didn't help. I didn't really consider low voltage since the battery will turn the thing over for what seems like a much longer time than it should, and comes right back up when it does start. But, low cranking voltage is not a bad thing to check. I know the Jacobs on the '57 won't tolerate being given anything less than 12 volts.

You're correct about the ignition having it's own controller. But, the ECM still controls timing, so there is some interface there.

Thanks again for the suggestions. Too late to go check now, more tomorrow...

Vader

57,

Please, put down the Browning... A 12 ga. slug will only make the problems worse.

It sounds like you have the digital "stepped" EGR. If one of the ports is stuck open, you could have some EGR leakage all the time. Once running, the PCM will adjust a whole host of parameters to keep it idling/running well, despite the leak, but protracted cranking could be a result. I've heard some techs have the 231s come in with a completely dead cylinder, and the only complaint from the owners is a little less power and poor mileage. They could never tell from the idle quality.

You also have the coil packs - just something else to consider - along with the crank position sensor and low voltage.

The CTS is a very significant input to the PCM. Spark advance/retard, fuel trim, starting fuel, shift points, EGR and EVAP operation, BLM writes, TCC lockup, and a host of other items rely heavily on the CTS for correct readings. The IAT is also important. The CTS and IAT/MAT must be within ten degrees of each other and below 41°C to enable the cold start enrichment routine.

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Later,
Vader
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"Make Me Bad..."
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five7kid

iTrader: (14)

I was all set to go buy the coil pack and controller (cheaper than the EGR valve). Now you have me wondering.

This has been going on for almost 9 months, and I just got the 1st code in the last week. I believe those EGR valves are feedback, and not getting the expected response is how you get a code - correct? But, port leakage would most likely not set a code.

Aw, heck, might as well replace the coil pack, controller and EGR. Still cheaper than buying a different car. And, the Browning can be messy...

GMTech

Don't waste your money on the coils and ICM (ignition control module). Most people think that these are a "cure all" for the DIS cars, but in reality they do not fail as much as everybody thinks. I don't know how many times I have seen people all pissed off because they spent $$$$$$ on coils and module, and it runs the same or worse.

The EGR problem may be valid, and I would investigate that first. You could simply remove the EGR, cut a soda can out to fit the shape of the EGR valve's mating surface, and bolt the EGR back up, with the metal in between. This will prevent any EGR flow if indeed one of the ports are stuck.

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five7kid

iTrader: (14)

I hadn't spent the money yet. Interesting diagnostic approach, however.

Any negative effects from blocking off the EGR (other than emissions, that is)? I've got plenty of soda cans - will try that soon.

GMTech

Its just a temporary. If you leave it, the first time the ECM runs its EGR Diagnostic Executive (love those big terms), it will set an EGR code. I was just refering to leaving it in there for the "cold start".

------------------
If you live in Southeastern US, check us out!
South East Thirdgen


ASE Master Tech + L1
Savannah, GA

'87 Trans Am
S/D TPI retrofit including functional PassKey, 22# injectors,
JET AFPR, Ported Plenum,
TB Coolant Bypass, Custom Cold Air,
SSM SFC, KYB Shocks, Boxed LCAs, Wonder Bar,
8mm Accel wires,
Flowmaster Exhaust,
16" GTA rims,
Corvette Servo,
-->14.97 @ 94.9 MPH<--

'97 Bonneville SSE

five7kid

iTrader: (14)

Update:

Put on a "known-good" EGR valve, no difference.

Swapped the coil pack and ignition module (together) with our '90 SSE tonight. Guess what?


They both start great now!!!!


I'll check in the morning when they're both cold, but perhaps I disturbed a marginal contact in one of the circuits and "cured" it.

Edit update, morning after: The problem child started first try (haven't seen that in a long time). The '90 started on second try (not unusual for it), but at least it fired on the first try before it died. May not be out of the woods yet, but looks like we're on the right path.

[This message has been edited by five7kid (edited February 16, 2001).]